JP2010007153A - Plating apparatus and plating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a plated film with more uniform film thickness on the whole surface of a substrate even when the substrate has a higher sheet resistance on its surface. <P>SOLUTION: The plating apparatus includes: a sealing material 90 which abuts on a peripheral part of the surface of the substrate W and seals the peripheral part; a cathode contact point 88 which comes into contact with an electroconductive layer formed on the surface of the substrate W and energizes the substrate W; an electrode head 28 that has a plating-solution chamber 100 partitioned and formed therein which accommodates an anode 98 in a housing 94 and arranges a porous body 110 in an open end portion; a drive mechanism 136 that moves the electrode head 28 from a first plating position to a second plating position at which the porous body 110 is more distant from the substrate W than at the first plating position, and stops the electrode head 28 there, while filling a space between the substrate W and the porous body 110 with the plating solution; and an auxiliary cathode part 124 which is separately arranged from the substrate W in a position of facing the outer periphery of the substrate W and is immersed in the plating solution which fills the space between the substrate W and the porous body 110. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a plating apparatus and a plating method, and in particular, a metal (wiring material) such as copper is embedded in a fine wiring recess (circuit pattern) formed on the surface (surface to be plated) of a substrate such as a semiconductor wafer. The present invention relates to a plating apparatus and a plating method used to form a wiring.

  In recent years, as a metal material for forming LSI wiring on a semiconductor substrate, there has been a remarkable movement of using copper (Cu) having a low electrical resistivity and a high electromigration resistance instead of aluminum or an aluminum alloy. This type of copper wiring is generally formed by embedding copper in a fine wiring recess provided on the surface of the substrate. As a method of forming this copper wiring, there are methods such as CVD, sputtering, and plating, but in any case, copper is formed on almost the entire surface of the substrate, which is unnecessary by chemical mechanical polishing (CMP). Copper is removed.

FIG. 1 shows a manufacturing example of this type of copper wiring board in the order of steps. First, as shown in FIG. 1A, an insulating film 2 such as an oxide film made of SiO ₂ or a low-k material film is deposited on a conductive layer 1a on a semiconductor substrate 1 on which a semiconductor element is formed. Inside the insulating film 2, a contact hole 3 and a trench 4 are formed as wiring recesses by lithography and etching techniques. Then, a barrier layer 5 made of TaN, TiN or the like is formed thereon, and a seed layer 7 is formed thereon as a power feeding layer for electrolytic plating.

  Then, as shown in FIG. 1B, the surface of the seed layer 7 of the substrate W is plated with copper so that the contact holes 3 and the trenches 4 are filled with copper, and the copper film 6 is formed on the insulating film 2. To deposit. Thereafter, the copper film 6, the seed layer 7 and the barrier layer 5 on the insulating film 2 are removed by chemical mechanical polishing (CMP), and the surface of the copper film 6 filled in the contact hole 3 and the trench 4 The surface of the insulating film 2 is substantially flush with the surface. Thereby, as shown in FIG. 1C, a wiring made of the copper film 6 is formed inside the insulating film 2.

  As the seed layer 7, a copper seed layer formed by sputtering, CVD, ALD, electroless plating or the like is generally used, and the thickness of the copper seed layer increases year by year as the wiring size becomes finer. It is getting thinner. For example, the thickness of the copper seed layer when manufacturing a 65 nm generation semiconductor device is around 600 angstroms in the substrate field portion, but when the 45 nm generation is reached, it is expected to be 500 angstroms or less. In the next and next generations, it is expected that the thickness of the copper seed layer will be 300 angstroms or less, or that copper will be plated directly on the surface of a barrier layer made of, for example, ruthenium without providing a copper seed layer. ing.

  In the copper seed layer having the conventional film thickness, since its electric resistance (sheet resistance) is 1Ω / sq or less, a resistor is inserted between the cathode and the substrate connected to the cathode contact. Alternatively, by reducing the acid concentration of the plating solution to increase the resistance of the plating solution itself, the terminal effect that depends on the sheet resistance of the seed layer is reduced, and the film thickness is increased at the central portion of the substrate at the peripheral portion. A copper film having a uniform film thickness that is prevented from becoming thinner can be formed on the surface of the substrate.

  The applicant, as a high-resistance structure composed of a porous body having an electrical resistivity greater than the electrical resistivity of the plating solution, disposed between the substrate and the anode, has an electrical resistance at the outer periphery as compared with the central portion. It has been proposed to use one having a large value (see Patent Document 1). In addition, a plurality of divided anodes are used as anodes, and a plating power source is individually connected to each of these divided anodes. For example, the anode is positioned on the center side only for a certain period of time to form an initial plating film on the substrate. This is the case when the sheet resistance is high by increasing the current density of the split anode from the periphery to prevent the plating current from concentrating on the outer periphery of the substrate and allowing the plating current to flow to the center side of the substrate. However, the thing which enabled it to form the plating film of a uniform film thickness was proposed (refer patent document 2).

  Furthermore, in order to obtain a uniform plating film on the entire surface of the substrate, it has been proposed to dispose the auxiliary electrode in a plating solution (electrolytic solution) at a position corresponding to the outer peripheral portion of the substrate. (See Patent Document 3).

Japanese Patent Laid-Open No. 2002-4091 JP 2002-129383 A JP 2002-506488 A

  In the next-generation and next-generation semiconductor devices, where the wiring size is further miniaturized, the thickness of the copper seed layer becomes thinner and the copper seed layer has a sheet resistance of 1 Ω / sq or more. When copper is directly plated on the surface of a barrier layer made of ruthenium or the like without providing a layer, the sheet resistance is expected to be 10 Ω / sq or more. In such a case, the countermeasures against the terminal effect depending on the sheet resistance are insufficient only by inserting the resistor between the substrate and the anode and increasing the resistance of the plating solution itself. It is considered that it is difficult to form a copper film having a uniform film thickness over the entire surface of the substrate.

  For example, when plating is performed by placing a porous body whose electric resistance is adjusted so that the electric resistance of the outer peripheral portion is larger than that of the central portion between the substrate and the anode, a plating film is deposited on the seed layer of the substrate. As the sheet resistance of the plating film decreases, the plating film is more easily attached to the central portion of the substrate than the outer peripheral portion of the substrate.

  The present invention has been made in view of the above circumstances, and a plating apparatus and a plating method capable of forming a plating film having a uniform film thickness on the entire surface of a substrate even on a substrate having a higher sheet resistance on the surface. The purpose is to provide.

  According to the first aspect of the present invention, there is provided a substrate holding portion that holds a substrate, a sealing material that contacts a peripheral portion of the substrate surface held by the substrate holding portion and seals the peripheral portion, and is held by the substrate holding portion. A cathode contact for contacting and energizing the conductive layer formed on the surface of the substrate, and a porous body disposed at the open end facing the substrate held in the housing and held by the substrate holding portion of the housing The electrode head is separated from the first plating position while the plating solution is filled between the electrode head in which the plating solution chamber is partitioned, the substrate held by the substrate holding portion, and the porous body. A drive mechanism for stopping the substrate by moving it to a second plating position where the distance between the substrate and the porous body is greater than the position, and a position facing the outer peripheral portion of the substrate held by the substrate holding part. Placed on the substrate A plating apparatus characterized by comprising an auxiliary cathode portion to be immersed in the plating solution filled between the substrate held by sandwiching member and the porous body.

  As a countermeasure for the terminal effect, for example, a porous body adjusted so that the electrical resistance of the outer peripheral part is larger than the central part is arranged between the substrate and the anode, and the surface of the seed layer or the like having a high sheet resistance is plated. When done, because plating is easily attached to the center of the substrate, uniform plating can be performed from the outer periphery of the substrate to the center of the substrate from the beginning of plating, but as the plating film grows and the sheet resistance of the plating film decreases, A plating film thickness distribution is obtained in which the central portion of the substrate is excessively plated and the central portion is raised. According to the present invention, the electrode head containing the anode therein is moved from the first plating position to the second plating position where the distance between the substrate and the porous body is farther than the first plating position and stopped. By performing the latter plating, the growth of the plating film near the center of the substrate is moderately suppressed, and the auxiliary cathode part is used in combination to control the film thickness of the plating film formed on the outer peripheral part of the substrate. Thus, a plating film having a uniform thickness can be formed on the entire surface of the substrate.

The invention according to claim 2 is the plating apparatus according to claim 1, wherein the porous body is adjusted so that the electric resistance of the outer peripheral portion is higher than that of the central portion.
Adjusting the porous body so that the electrical resistance of the outer peripheral portion is higher than that of the central portion by adjusting at least one of the outer shape, the internal structure of the porous body, or the mounting of members having different electrical conductivities Can do.

  A third aspect of the present invention is the plating apparatus according to the first or second aspect, further comprising a power source connected to the cathode contact and the auxiliary cathode portion, respectively.

  According to a fourth aspect of the present invention, a plating solution is filled between the conductive layer on the surface of the substrate in contact with the cathode contact and the anode disposed at a position facing the conductive layer, and the substrate in the plating solution is filled with the plating solution. A porous body is disposed at a position facing the central portion, and an auxiliary cathode portion is disposed at a position facing the outer peripheral portion, spaced apart from the substrate, and initial plating is performed by applying a voltage between the anode and the cathode contact. And performing late plating by moving the porous body to a position away from the substrate and stopping while applying a voltage between the anode and the cathode contact and between the anode and the auxiliary cathode. This is a plating method.

  According to the present invention, after the initial plating, the porous body is moved to a position away from the substrate and stopped while applying a voltage between the anode and the cathode contact and between the anode and the auxiliary cathode portion, and the latter plating is performed. Therefore, the electric field concentrated in the central part of the substrate is dispersed by the edge effect to moderately suppress the plating growth in the central part of the substrate. A plating film having a uniform film thickness can be formed on the entire surface of the substrate regardless of the film thickness.

The invention according to claim 5 is characterized in that the conductive layer of the substrate has at least one of Cu, Ru, Ta, TaN, W, WNC, WC, Pt, ITO, Ti, TiW, or T ₂ N. The plating method according to claim 4.
A substrate with a seed layer with a higher resistance than copper, such as ruthenium, can be handled by adjusting the electrical resistance inside and outside the porous body even if the sheet resistance value of the plating base increases and the terminal effect effect becomes stronger. It can also be applied to.

  According to the present invention, when plating is performed using a porous body that concentrates an electric field at the center of the substrate as a countermeasure for the terminal effect, the distance between the porous body and the substrate is increased during plating, and the auxiliary cathode portion is further provided. In combination, after the plating film reaches a predetermined film thickness, the electric field specialized for the central part of the substrate can be made uniform, and a plating film with a uniform film thickness can be formed on the entire surface of the substrate. it can.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this example, as shown in FIG. 1A, the resistivity is equal to or higher than that of copper, for example, Cu, Ru, Ta, TaN, W, WNC, WC, Pt, ITO, Ti, TiW or T ₂ N As shown in FIGS. 1B to 1C, a substrate W such as a semiconductor wafer having a seed layer (conductive layer) 7 having any of the above is prepared, and the surface of the substrate W is subjected to electrolytic copper plating. An example is shown in which a wiring made of a copper film 6 is formed in a fine wiring recess provided on the substrate surface.

  FIG. 2 shows an overall layout of the substrate processing apparatus provided with the plating apparatus according to the embodiment of the present invention. As shown in FIG. 2, this substrate processing apparatus includes two load / unload units 10 that are located in the same facility and house a plurality of substrates W therein, and two platings that perform plating. A transport robot 14 for delivering the substrate W between the apparatus 12, the load / unload unit 10 and the plating apparatus 12, and a plating solution supply facility 18 having a plating solution tank 16 are provided.

  As shown in FIG. 3, the plating apparatus 12 includes a substrate processing unit 20 that performs a plating process and an incidental process thereof, and a plating solution tray 22 that stores a plating solution is disposed adjacent to the substrate processing unit 20. ing. Further, an electrode arm portion 30 having an electrode head 28 that is held at the tip of a swing arm 26 that swings about the rotation shaft 24 and swings between the substrate processing unit 20 and the plating solution tray 22 is provided. Yes. Further, a precoat / recovery arm 32 and a fixed nozzle 34 for injecting a chemical solution such as pure water or ionic water, gas, or the like toward the substrate are disposed on the side of the substrate processing unit 20. In this example, three fixed nozzles 34 are provided, and one of them is used for supplying pure water.

  As shown in FIG. 4, the substrate processing unit 20 includes a substrate holder 36 that holds the substrate W with the substrate surface (surface to be plated) facing upward, and a peripheral portion of the substrate holder 36 above the substrate holder 36. The cathode portion 38 is provided so as to surround the. Furthermore, a bottomed substantially cylindrical scattering prevention cup 40 that surrounds the periphery of the substrate holder 36 and prevents the scattering of various chemicals used during processing is arranged to be movable up and down via an air cylinder (not shown). ing.

  Here, the substrate holder 36 is moved up and down between a lower substrate delivery position A, an upper plating position B, and an intermediate pretreatment / cleaning position C by an air cylinder 44, and a rotary motor (not shown) It is configured to rotate integrally with the cathode portion 38 at an arbitrary acceleration and speed via a belt. Opposite this substrate delivery position A, a substrate carry-in / out port (not shown) is provided on the side of the frame side of the plating apparatus 12 on the side of the transfer robot 14, and when the substrate holder 36 is raised to the plating position B, A sealing member 90 and a cathode contact 88 of the following cathode portion 38 are in contact with the peripheral edge portion of the substrate W held by the holder 36. On the other hand, the upper end of the anti-scattering cup 40 is located below the substrate carry-in / out entrance, and as shown by the phantom line in FIG. Yes.

  The plating solution tray 22 is used to wet the following porous body 110 and the anode 98 of the electrode arm portion 30 with the plating solution when the plating process is not performed, and has a size that can accommodate the porous body 110. And has a plating solution supply port and a plating solution drain port (not shown). In addition, a photo sensor is attached to the plating solution tray 22 so that the plating solution in the plating solution tray 22 is fully filled, that is, overflow and drainage can be detected.

  The electrode arm section 30 is moved up and down via a drive mechanism 136 having a vertical movement motor 132 and a ball screw 134, which are servo motors, as described below, and the plating solution tray 22 and the substrate processing section via a turning motor. 20 (swing). A pneumatic actuator may be used instead of the motor.

  As shown in FIG. 5, the precoat / recovery arm 32 is connected to the upper end of a support shaft 58 extending in the vertical direction, pivots (swings) via a rotary actuator 60, and passes through an air cylinder (not shown). Are configured to move up and down. The precoat / collection arm 32 holds a precoat nozzle 64 for discharging a precoat liquid on the free end side, and a plating solution recovery nozzle 66 for collecting a plating liquid on the base end side. The precoat nozzle 64 is connected to a syringe driven by an air cylinder, for example, and the precoat liquid is intermittently discharged from the precoat nozzle 64, and the plating solution recovery nozzle 66 is connected to, for example, a cylinder pump or an aspirator. The plating solution on the substrate is sucked from the plating solution recovery nozzle 66.

  As shown in FIGS. 6 to 8, the substrate holder 36 includes a disk-shaped substrate stage 68, and the substrate W is horizontally placed on the upper surface at six locations along the circumferential direction of the peripheral portion of the substrate stage 68. A support arm 70 is erected to be placed and held on the head. A positioning plate 72 is fixed to one upper end of the support arm 70 to be positioned in contact with the end surface of the substrate W, and a substrate is fixed to the upper end of the support arm 70 facing the support arm 70 to which the positioning plate 72 is fixed. A pressing piece 74 is pivotally supported so as to be rotated in contact with the end face of W and press the substrate W against the positioning plate 72 side. In addition, chuck claws 76 that pivot and press the substrate W downward from above are rotatably supported at the upper ends of the other four support arms 70.

  Here, the lower end of the pressing piece 74 and the chuck claw 76 is connected to the upper end of the pressing bar 80 biased downward via the coil spring 78, and the pressing piece 74 and the chuck are moved along with the downward movement of the pressing bar 80. A claw 76 is pivoted inwardly and closed, and a support plate 82 is disposed below the substrate stage 68 so as to abut the lower surface of the pressing rod 80 and push it upward.

  As a result, when the substrate holder 36 is positioned at the substrate delivery position A shown in FIG. 4, the pressing rod 80 abuts on the support plate 82 and is pushed upward, and the pressing piece 74 and the chuck claw 76 rotate outward. Then, when the substrate stage 68 is raised, the pressing rod 80 is lowered by the elastic force of the coil spring 78, and the pressing piece 74 and the chuck pawl 76 are rotated inward and closed.

  As shown in FIGS. 9 and 10, the cathode portion 38 includes an annular frame 86 fixed to the upper end of a column 84 erected on the peripheral edge of a support plate 82 (see FIG. 8 and the like), and the frame 86. In this example, the cathode contact 88 is divided into six parts and attached to the lower surface, and an annular seal member 90 is attached to the upper surface of the frame 86 so as to cover the upper side of the cathode contact 88. ing. The seal member 90 is configured such that an inner peripheral edge thereof is inclined downward inward and gradually becomes thin, and an inner peripheral end portion hangs downward.

As a result, as shown in FIG. 4, when the substrate holder 36 is moved up to the plating position B, the cathode contact 88 is pressed against the peripheral edge of the substrate W held by the substrate holder 36 and energized. The inner peripheral edge is pressed against the upper surface of the peripheral edge of the substrate W, and this is sealed watertight to prevent the plating solution supplied to the upper surface of the substrate (surface to be plated) from seeping out from the edge of the substrate W. In addition, the plating solution is prevented from contaminating the cathode contact 88.
In this example, the cathode portion 38 cannot move up and down and rotates integrally with the substrate holder 36. However, the cathode portion 38 can move up and down, and the seal member 90 is pressed against the surface to be plated of the substrate W when lowered. You may comprise so that it may do.

  As shown in FIGS. 11 and 12, the electrode head 28 of the electrode arm portion 30 includes a housing 94 suspended from the free end of the swing arm 26 and a porous hole disposed so as to close the lower end opening of the housing 94. And a material 110. That is, an inward projecting portion 94a projecting inward is provided at the lower portion of the housing 94, and a flange portion 110a is provided at the upper portion of the porous body 110, and the flange portion 110a is hooked on the inward projecting portion 94a. As a result, the porous body 110 is held in the housing 94. As a result, a hollow plating solution chamber 100 is defined in the housing 94.

  The porous body 110 is composed of a porous ceramic such as alumina, SiC, mullite, zirconia, titania, cordierite, or the like, or a hard porous body such as a sintered body of polypropylene or polyethylene, or a composite thereof. For example, in the case of alumina-based ceramics, the pore diameter is 30 to 200 μm, and in the case of SiC, the pore diameter is 30 μm or less, the porosity is 20 to 95%, the thickness is 1 to 20 mm, preferably 5 to 20 mm, and more preferably 8 to About 15 mm is used. In this example, the porous body 110 is composed of an alumina porous ceramic plate. And, by containing the plating solution inside this, that is, the porous ceramic plate itself is an insulator, by allowing the plating solution to enter inside intricately and by following a fairly long path in the thickness direction, It is comprised so that it may have an electrical conductivity smaller than the electrical conductivity of a plating solution.

The porous body 110 is adjusted so that the electrical resistance of the outer peripheral portion is higher than that of the central portion. In this example, towards the proportion of the central portion _{E 1} definitive pores 110b of the porous member 110 shown in FIG. 13 (a), the proportion of pores 110b at the outer peripheral portion _{E 2} of the porous body 110 shown in FIG. 13 (b) The porosity distribution is such that the porosity gradually decreases gradually from the center of the porous body 110 toward the outer periphery.

  As described above, the porous body 110 is arranged in the plating solution chamber 100 and a large resistance is generated by the porous body 110, whereby the sheet resistance of the seed layer (conductive layer) 7 shown in FIG. Therefore, the in-plane uniformity of the plating film can be improved by reducing the in-plane difference of the current density due to the sheet resistance on the surface of the substrate W. In particular, by using the porous body 110 adjusted so that the electric resistance of the outer peripheral portion is larger than that of the central portion, the central portion of the substrate is likely to be plated on the surface of the seed layer (conductive layer) having a high sheet resistance. It is possible to perform plating under conditions.

  A band-shaped insulator 112 is wound around the outer peripheral surface of the porous body 110 so as to surround it. The insulator 112 is made of a stretchable material such as fluoro rubber. As described above, by winding the insulator 112 around the outer peripheral surface of the porous body 110, it is possible to prevent current from being concentrated in the vicinity of the outer peripheral portion of the substrate W.

  An anode 98 is disposed in the plating solution chamber 100. The anode 98 is generally composed of copper (phosphorus-containing copper) containing phosphorus with a content of 0.03 to 0.05% in order to suppress the production of slime. In this example, for example, an insoluble anode made of an insoluble metal such as platinum or titanium or an insoluble electrode obtained by plating platinum on a metal is used as the anode 98. As described above, by using an insoluble anode as the anode 98, it is possible to prevent a change in shape due to the dissolution of the anode 98 and always maintain a constant discharge state without replacing the anode 98.

  On the upper surface of the housing 94, a plating solution introduction port 104 for introducing a plating solution into the inside is provided, and a plating solution supply pipe 102 extending from the plating solution supply facility 18 (see FIG. 2) is connected to the plating solution introduction port 104. Has been. Further, a plating solution discharge pipe 106 extending from the plating solution supply facility 18 is connected to a plating solution discharge port 108 provided on the upper surface of the housing 94.

  A ring-shaped plating solution weir 120 is attached to a position surrounding the housing 94 of the electrode head 28 on the upper surface of the sealing material 90 to prevent the plating solution from flowing out to the outside. A plating solution injection part 122 is provided between the housing 94 and the plating solution weir 120. In the plating solution injection unit 122, when the substrate holding unit 36 is at the plating position B (see FIG. 4), the gap between the substrate W held by the substrate holding unit 36 and the porous body 110 is, for example, about 0.5 to 3 mm. In this state, the electrode head 28 is lowered, and in this state, the plating solution is injected from the side of the housing 94 into the region surrounded by the sealing material 90 between the substrate W and the porous body 110. The nozzle portion at the lower end opens in a region sandwiched between the housing 94 and the plating solution weir 120. At this time, the plating solution is injected until it reaches above the sealing material 90, and the outflow of the plating solution reaching above the sealing material 90 is blocked by the plating solution weir 120.

  A ring-shaped auxiliary cathode portion 124 is attached to the upper surface of the inclined portion of the sealing material 90 and is located inside the plating solution weir 120. The auxiliary cathode portion 124 is located at a position corresponding to the peripheral edge portion of the substrate W held by the substrate holding portion 36 and is surrounded by the sealing material 90 between the substrate W and the porous body 110 as described above. When the plating solution is injected into the region, it is immersed in the injected plating solution.

  The cathode contact 88 is electrically connected to the cathode of the plating power supply 126, the anode 98 is electrically connected to the anode of the plating power supply 126, the auxiliary cathode portion 124 is electrically connected to the cathode of the auxiliary power supply 128, and the anode 98 is electrically connected to the anode of the auxiliary power supply 128. Connected.

  The electrode head 28 is suspended and held by the swing arm 26, and the swing arm 26 is configured to move up and down via a drive mechanism 136 having a vertical movement motor 132 formed of a servo motor and a ball screw 134. ing. After the initial plating, the drive mechanism 136 moves the electrode head 28 from the first plating position to the first plating position while the plating solution is filled between the substrate W held by the substrate holding unit 36 and the porous body 110. The substrate W is moved to the second plating position where the distance between the porous body 110 and the porous body 110 is increased, and is stopped.

That is, when performing electrolytic plating, when the substrate holder 36 is at the plating position B (see FIG. 3), as shown by a two-dot chain line in FIG. 12, the substrate W held by the substrate holder 36 and the porous body 110 distance _{D 1} is, lowers the first plating position to the electrode head 28, for example of the order of 0.1 to 3 mm, in this state, the sealing material clearance from the plating solution injection section 122 and the substrate W and the porous body 110 90 The plating solution is injected into the area surrounded by. At this time, the plating solution reaches the upper part of the sealing material 90 and injects the plating solution until the auxiliary cathode portion 124 is immersed in the plating solution, and the plating solution that reaches the upper side of the sealing material 90 is dammed by the plating solution dam 120. stop. Then, initial plating is performed by applying a predetermined voltage between the cathode contact 88 and the anode 98 via the plating power source 126.

After plating for a predetermined time, the auxiliary cathode part 124 and the anode 98 are further connected via the auxiliary power supply 128 while a predetermined voltage is applied between the cathode contact 88 and the anode 98 via the plating power supply 126. increasing the predetermined auxiliary while applying a voltage, the second plating position to the electrode head 28 a distance D ₂ between the substrate W and the porous body 110 held by the substrate holder 36 to be, for example 3~50mm about between the In this way, late plating is performed.

Here, as the porous member 110, as to use a difference in electrical resistance between the center portion and the peripheral portion is large, it is possible to widen the distance D ₂ of the porous member 110 and the substrate W in the second plating position desired . However, the electric field is widened more than necessary the distance D ₂ of the porous member 110 and the substrate W in the second plating position becomes too concentrated in the outer peripheral portion of the substrate W, the plated film center portion of the substrate W is lowered prime It becomes a film thickness distribution. Therefore, the distance _{D 2} of the porous member 110 and the substrate W in the second plating position is preferably 50mm or less.

  The current flowing through the auxiliary cathode portion 124 varies depending on the resistance value of the substrate and the device configuration, but is basically smaller than the current flowing through the substrate. The timing at which the distance between the porous body 110 and the substrate W starts to be separated, that is, the timing at which the electrode head 28 is raised from the first plating position to the second plating position, It can be arbitrarily determined depending on the difference and conditions such as the sheet resistance of the seed layer (conductive film) 7 shown in FIG. For example, the plating time is maintained until the plating film formed on the surface of the seed layer 7 becomes uniform by performing plating while maintaining the electrode head 28 at the first plating position and without applying the auxiliary power supply 128. Can be determined by separating the distance between the porous body 110 and the substrate W or applying an auxiliary power source at a later time.

  In this way, late plating is performed in a state where the electrode head 28 is moved from the first plating position to the second plating position where the distance between the substrate W and the porous body 110 is further away from the first plating position and stopped. Thus, the growth of the plating film in the vicinity of the center of the substrate W is moderately suppressed, and the thickness of the plating film formed on the outer peripheral portion of the substrate W is controlled by using the auxiliary cathode portion 124 together. Thus, a plating film having a uniform film thickness can be formed on the entire surface of the substrate. In particular, since the entire surface can be uniformly plated while concentrating the electric field at the center of the substrate, it is possible to cope with a 450 mm large-diameter wafer having a stronger terminal effect effect.

Next, the operation of the substrate processing apparatus provided with the plating apparatus will be described.
First, the substrate W before plating processing is taken out from the load / unload unit 10 by the transfer robot 14, and one plating apparatus is provided from the substrate loading / unloading port provided on the side surface of the frame with the surface (surface to be plated) facing upward. 12 to the inside. At this time, the substrate holder 36 is in the lower substrate delivery position A, and the transfer robot 14 lowers the hand after the hand has reached just above the substrate stage 68, thereby moving the substrate W onto the support arm 70. Placed on. Then, the hand of the transfer robot 14 is retreated through the substrate carry-in / out entrance.

  After the removal of the hand of the transfer robot 14 is completed, the anti-scattering cup 40 is raised, and at the same time, the substrate holder 36 at the substrate delivery position A is raised to the pretreatment / cleaning position C. At this time, with this rise, the substrate placed on the support arm 70 is positioned by the positioning plate 72 and the pressing piece 74 and is securely gripped by the chuck claws 76.

  On the other hand, the electrode head 28 of the electrode arm portion 30 is at a normal position on the plating solution tray 22 at this time, and the porous body 110 or the anode 98 is located in the plating solution tray 22 and is scattered in this state. Simultaneously with the rise of the prevention cup 40, supply of the plating solution to the plating solution tray 22 and the electrode head 28 is started. Then, until the substrate plating process is started, a new plating solution is supplied, and suction through the plating solution discharge pipe 106 is performed to replace the plating solution contained in the porous body 110 and remove bubbles. When the raising of the scattering prevention cup 40 is completed, the substrate carry-in / out entrance on the side of the frame is closed and closed by the scattering prevention cup 40, and the atmosphere inside and outside the frame is cut off.

  When the anti-scattering cup 40 rises, the precoat process is started. That is, the substrate holder 36 that has received the substrate W is rotated, and the precoat / collection arm 32 that is in the retracted position is moved to a position facing the substrate. When the rotation speed of the substrate holder 36 reaches a set value, a precoat liquid made of, for example, a surfactant is intermittently applied to the surface to be plated of the substrate from a precoat nozzle 64 provided at the tip of the precoat / collection arm 32. Discharge. At this time, since the substrate holder 36 is rotating, the precoat liquid reaches the entire surface of the substrate W to be plated. Next, the precoat / collection arm 32 is returned to the retracted position, the rotational speed of the substrate holder 36 is increased, and the precoat liquid on the surface to be plated of the substrate W is shaken off and dried by centrifugal force.

  After pre-coating is completed, the process proceeds to plating. First, the substrate holder 36 is raised to a plating position B where plating is performed in a state where the rotation is stopped or the rotation speed is reduced to the plating speed. Then, the peripheral portion of the substrate W comes into contact with the cathode contact 88 and can be energized. At the same time, the sealing material 90 is pressed against the upper surface of the peripheral portion of the substrate W, and the peripheral portion of the substrate W is sealed watertight. .

On the other hand, based on the signal that the precoat process of the loaded substrate W has been completed, the electrode arm unit 30 is swung horizontally from above the plating solution tray 22 so that the electrode head 28 is positioned above the position where the electrolytic process is performed. After reaching this position, the electrode head 28 is lowered toward the cathode portion 38, and the distance D between the porous body 110 and the substrate W without the porous body 110 coming into contact with the surface to be plated of the substrate W. _{When 1} reaches the first plating position close to about 0.1 mm to 3 mm, the descent of the electrode head 28 is stopped.

  In this state, the plating solution reaches the area above the sealing material 90 from the plating solution injection part 122 to the region surrounded by the sealing material 90 in the gap between the substrate W and the porous body 110, and the auxiliary cathode part 124 becomes the plating solution. The plating solution is poured until it is immersed in the plate, and the plating solution reaching above the sealing material 90 is blocked by the plating solution weir 120. Then, initial plating is performed by applying a predetermined voltage between the cathode contact 88 and the anode 98 via the plating power source 126.

After plating for a predetermined time, the auxiliary cathode part 124 and the anode 98 are further connected via the auxiliary power supply 128 while a predetermined voltage is applied between the cathode contact 88 and the anode 98 via the plating power supply 126. increasing the predetermined auxiliary while applying a voltage, the second plating position to the electrode head 28 a distance D ₂ between the substrate W and the porous body 110 held by the substrate holder 36 to be, for example 3~50mm about between the In this way, late plating is performed.

  As a result, even on the substrate W having a high sheet resistance, a plating film having a uniform film thickness is formed on the entire surface of the conductive film such as the seed layer 7, and the plating metal is formed into fine concave portions including the contact holes 3 and the trenches 4. (Refer to FIG. 1) It can be reliably embedded without causing voids.

  When the plating process is completed, the electrode arm portion 30 is raised and turned to return the electrode head 28 to the upper side of the plating solution tray 22 and lowered to the normal position. Next, the precoat / recovery arm 32 is moved from the retracted position to a position facing the substrate W and lowered, and the plating solution remaining solution on the substrate W is recovered from the plating solution recovery nozzle 66. After the collection of the remaining liquid is completed, the precoat / collection arm 32 is returned to the retracted position, and pure water is discharged from the fixed nozzle 34 for pure water onto the central portion of the substrate W in order to rinse the plating surface of the substrate. At the same time, the substrate holder 36 is rotated at an increased speed to replace the plating solution on the surface of the substrate W with pure water. Thus, by rinsing the substrate W, when the substrate holder 36 is lowered from the plating position B, the plating solution splashes and the cathode contact 88 of the cathode portion 38 is prevented from being contaminated.

  After rinsing, the water washing process is started. That is, the substrate holder 36 is lowered from the plating position B to the pretreatment / cleaning position C, and the substrate holder 36 and the cathode portion 38 are rotated while supplying pure water from the fixed nozzle 34 for pure water, and water washing is performed. At this time, the sealing material 90 and the cathode contact 88 can be cleaned simultaneously with the substrate by pure water directly supplied to the cathode portion 38 or pure water scattered from the surface of the substrate W.

  After the water washing is completed, the drying process is started. That is, the supply of pure water from the fixed nozzle 34 is stopped, the rotation speed of the substrate holder 36 and the cathode portion 38 is increased, and the pure water on the substrate surface is shaken off by the centrifugal force and dried. At the same time, the sealing material 90 and the cathode contact 88 are also dried. When the drying process is completed, the rotation of the substrate holder 36 and the cathode portion 38 is stopped, and the substrate holder 36 is lowered to the substrate delivery position A. Then, the grip of the substrate W by the chuck claws 76 is released, and the substrate W is placed on the upper surface of the support arm 70. At the same time, the splash prevention cup 40 is also lowered.

  Thus, the plating process and all the pre-processing and cleaning / drying processes incidental thereto are completed, and the transfer robot 14 inserts the hand from the substrate carry-in / out port below the substrate W and lifts the substrate as it is, thereby The processed substrate W is received from the holder 36. Then, the transfer robot 14 returns the processed substrate W received from the substrate holder 36 to the load / unload unit 10.

In the above example, as the porous body 110, the ratio of the pores in the central part is higher than the ratio of the pores in the outer peripheral part, and the porosity gradually gradually continues from the central part toward the outer peripheral part. Although what is comprised so that it may have the porosity distribution which becomes low is used, as shown in FIG. 14, several porous bodies 140a-140d which changed the porosity in steps are concentrically combined. Thus, the porous body 140 adjusted so that the electric resistance of the outer peripheral portion is higher than that of the central portion may be configured.
Next, examples of the present invention will be described, but the present invention is of course not limited to the following examples.

(Example)
A 300 mm substrate W having ruthenium having a sheet resistance of 300Ω / sq as a conductive layer was prepared, and a copper plating film having a thickness of 500 nm was grown on the surface of the ruthenium film using the above-described plating apparatus.

First, as Comparative Example 1, the electrode head 28 is lowered until the distance D ₁ (see FIG. 12) between the substrate W held by the substrate holder 36 and the porous body 110 becomes 0.5 mm, and in this state, the plating solution A plating solution is injected from the injection portion 122 into a region surrounded by the sealing material 90 in the gap between the substrate W and the porous body 110, and a plating current of 6.8 A is passed between the anode 98 and the ruthenium film of the substrate. Then, plating was performed for 150 seconds, whereby a 500 nm copper plating film was grown on the surface of the ruthenium film. FIG. 15 shows the relationship between the thickness of the plating film substrate positioned in the initial plating film P ₁ and the final plating film P ₂ at this time. This 15, even if a flat plating film as the initial plating film P _1, the final plating film P ₂ it is understood that a film thickness distribution raised in the central portion of the substrate.

Next, as Comparative Example 2, the electrode head 28 is lowered to the first plating position where the distance D ₁ (see FIG. 12) between the substrate W held by the substrate holder 36 and the porous body 110 is 0.5 mm. In this state, the plating solution is injected from the plating solution injection part 122 into the region surrounded by the sealing material 90 in the gap between the substrate W and the porous body 110, and 6.8 A is interposed between the anode 98 and the ruthenium film of the substrate. Initial plating was performed for 14 seconds by passing a plating current. Thereafter, the second plating position in which a distance D ₂ is 30mm and while passing a current of 6.8A, the substrate W and the porous body 110 held by the substrate holder 36 between the anode 98 and the substrate ruthenium film of The electrode head 28 was raised and stopped until a total of 150 seconds of plating was performed to grow a 500 nm copper plating film on the surface of the ruthenium film. With the relationship between the thickness of the case of the last plating film final plating and the substrate position in the film P ₂ plating film P ₃ Comparative Example the relationship between the thickness of the plating film substrate located in one shown in Figure 16. As shown in FIG. 16, after the initial plating film is formed, the distance between the porous body 110 and the substrate W is increased to 30 mm to perform plating, thereby dispersing the electric field and reducing the thickness of the plating film at the center of the substrate. I understand that I can do it.

Next, Example 1 of the present invention will be described. FIG. 18A shows the relationship between the plating time and the plating current and auxiliary current in Example 1, and FIG. 18B shows the relationship between the plating time and the distance between the porous body 110 and the substrate W. Show. As shown in FIG. 18, in Example 1, the electrode reaches the first plating position where the distance D ₁ (see FIG. 12) between the substrate W held by the substrate holder 36 and the porous body 110 is 0.5 mm. The head 28 is lowered, and in this state, the plating solution is injected from the plating solution injection part 122 into the region surrounded by the sealing material 90 in the gap between the substrate W and the porous body 110, and the anode 98 and the ruthenium film of the substrate During this period, a plating current of 6.8 A was applied to perform initial plating for 14 seconds. Thereafter, with a 6.8 A plating current flowing between the anode 98 and the ruthenium film of the substrate, a current of 1.0 A is further applied between the auxiliary cathode portion 124 and the anode 98 via the auxiliary power supply 128. while flowing, the distance D ₂ between the substrate W and the porous body 110 held by the substrate holder 36 is raised the second plating position to the electrode head 28 to be 30mm stopped, thereby, subjected to plating of total 150 seconds Then, a 500 nm copper plating film was grown on the surface of the ruthenium film. With the relationship between the thickness of the plating film substrate positioned in the final plating film P ₃ of Comparative Example 2 the relationship between the thickness of the substrate position and the plating film in the final plating film P ₄ at this time is shown in FIG. 17. As shown in FIG. 17, after the initial plating film is formed, the distance between the porous body 110 and the substrate W is increased to 30 mm while a current of 1.0 A (auxiliary current) is passed between the auxiliary cathode portion 124 and the anode 98 to further plate. It can be seen that by growing the film, the electric field concentrated on the outer peripheral portion of the substrate can be controlled and good plating can be performed on the entire surface of the substrate.

  The embodiment of the present invention has been described so far, but the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention may be implemented in various different forms within the scope of the technical idea.

It is a figure which shows the example which forms a copper wiring by plating process in order of a process. It is a top view which shows the whole substrate processing apparatus provided with the plating apparatus of embodiment of this invention. It is a top view which shows the plating apparatus shown in FIG. FIG. 3 is an enlarged cross-sectional view (cross-sectional view taken along line AA in FIG. 3) of a substrate holder and an electrode portion of the plating apparatus shown in FIG. It is a front view which shows the precoat and collection | recovery arm of the plating apparatus shown in FIG. It is a top view of the substrate holder of the plating apparatus shown in FIG. It is the BB sectional view taken on the line of FIG. It is CC sectional view taken on the line of FIG. It is a top view of the electrode part of the plating apparatus shown in FIG. FIG. 10 is a sectional view taken along line D-D in FIG. 9. It is a top view of the electrode arm part of the plating apparatus shown in FIG. It is sectional drawing when the electrolytic head which shows schematically the electrode head of the plating apparatus shown in FIG. 2, a cathode part, and a substrate holder is located in the 2nd plating position. FIG. 13A is a diagram showing the pore distribution in the central portion of the porous body, and FIG. 13B is a diagram showing the pore distribution in the outer peripheral portion of the porous body. It is sectional drawing which shows the other example of an anode. It is a graph which shows the relationship between the board | substrate position in the initial plating film of Comparative Example 1, and the last plating film, and the film thickness of a plating film. 10 is a graph showing the relationship between the substrate position and the film thickness of the plating film in the final plating film of Comparative Example 2 together with the relationship between the substrate position and the film thickness of the plating film in the final plating film of Comparative Example 1. 6 is a graph showing the relationship between the substrate position and the film thickness of the plating film in the final plating film of Example 1 together with the relationship between the substrate position and the film thickness of the plating film in the final plating film of Comparative Example 2. FIG. 18A is a graph showing the relationship between the plating time and the plating current and auxiliary current in Example 1, and FIG. 18B shows the relationship between the plating time and the distance between the porous body and the substrate. It is a graph to show.

Explanation of symbols

7 Seed layer (conductive layer)
DESCRIPTION OF SYMBOLS 10 Loading / unloading part 12 Plating apparatus 20 Substrate processing part 22 Plating solution tray 26 Oscillating arm 28 Electrode head 30 Electrode arm part 36 Substrate holder 38 Cathode part 40 Anti-scattering cup 68 Substrate stage 88 Cathode contact 90 Sealing material 94 Housing 98 Anode 100 Plating solution chamber 110, 140 Porous body 110b Pore 120 Plating solution weir 122 Plating solution injection part 124 Auxiliary cathode part 126 Plating power source 136 Drive mechanism

Claims (5)

A substrate holder for holding the substrate;
A sealing material that comes into contact with the peripheral portion of the substrate surface held by the substrate holding portion and seals the peripheral portion;
A cathode contact for contacting and energizing a conductive layer formed on the surface of the substrate held by the substrate holding unit;
An electrode head in which an anode is housed in a housing and a porous body is disposed at an opening end facing the substrate held by the substrate holding portion of the housing to partition the plating solution chamber;
While the plating solution is filled between the substrate held by the substrate holding part and the porous body, the electrode head is moved away from the first plating position from the first plating position than the first plating position. A drive mechanism for moving to the second plating position and stopping;
The substrate is held at a position facing the outer peripheral portion of the substrate held by the substrate holding unit and spaced from the substrate, and is immersed in a plating solution filled between the substrate held by the substrate holding unit and the porous body. A plating apparatus having an auxiliary cathode portion.   The plating apparatus according to claim 1, wherein the porous body is adjusted so that the electric resistance of the outer peripheral portion is higher than that of the central portion.   The plating apparatus according to claim 1, further comprising a power source connected to each of the cathode contact and the auxiliary cathode portion. A plating solution is filled between the conductive layer on the surface of the substrate in contact with the cathode contact and the anode disposed at a position facing the conductive layer,
A porous body at a position facing the central portion of the substrate in the plating solution, and an auxiliary cathode portion spaced from the substrate at a position facing the outer peripheral portion, respectively.
An initial plating is performed by applying a voltage between the anode and the cathode contact,
The late plating is performed by moving and stopping the porous body to a position away from the substrate while applying a voltage between the anode and the cathode contact and between the anode and the auxiliary cathode. Plating method. The plating method according to claim 4, wherein the conductive layer of the substrate has at least one of Cu, Ru, Ta, TaN, W, WNC, WC, Pt, ITO, Ti, TiW, or T ₂ N. .

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