JP2007149824A - Film forming method and film forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely embed the metal material such as copper at a high speed in such recess as a via hole of high aspect ratio and deep depth with no occurrence of voids inside. <P>SOLUTION: A substrate W is prepared which comprises a recess 202 with a conductive layer 206 formed on the surface including the interior of the recess 202. A polymer insulating film 208 is formed by electrodeposition method on the surface of the conductive layer 206 except for the interior of the recess 202. The electrolytic plating is applied on the surface of the substrate W where the polymer insulating film 208 is formed so that a metal material 210 is embedded in the recess 202. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a film forming method and a film forming apparatus for forming a metal film on the surface of a substrate such as a semiconductor wafer, and more particularly to the inside of a recess such as a fine trench or a via hole provided on the surface of a substrate such as a semiconductor wafer. The present invention relates to a film forming method and a film forming apparatus suitable for use in embedding a metal material or forming a wiring penetrating inside a semiconductor chip.

  In recent years, with the increase in integration and speed of semiconductor devices, multilayer wiring has been advanced. In this multilayer wiring, although miniaturization is progressing in the lower layer wiring, on the contrary, wiring and vias having a width exceeding 1 μm and a depth of several μm are used. In the three-dimensional mounting in which a plurality of semiconductor chips are combined into one package, a wiring that penetrates the semiconductor chip is formed from the conventional wiring formation between the semiconductor chips by wire bonding, and these wirings are connected to each other. As a result, the distance between wirings is shortened, and this is going to move toward lower power and higher speed. In this case, for example, it becomes necessary to fill a via hole (concave portion) having an opening size of 70 μm and a depth of about 100 μm with a metal material (wiring material). In order to form such a fine wiring with a deeper depth, the electrolytic plating method is considered most suitable from the viewpoint of economy.

  In a conventional electrolytic plating apparatus, for example, a defect such as a void is generated inside a via hole having a high aspect ratio and a depth of about 10 to 20 μm and a depth of about 70 to 150 μm provided inside the substrate. In general, it has been considerably difficult to embed a metal film (metal material) at high speed and reliably by electrolytic plating while preventing this. This is because as the plating on the surface of the substrate proceeds, the metal ions in the plating solution are remarkably consumed, and the supply of metal ions to the bottom of the via hole is delayed.

  For example, as shown in FIG. 1, electrolytic plating is performed on the surface of a conductive layer (seed layer) 6 covering an insulating film 4 having an asperity ratio as high as 1 or more and a deep via hole (concave portion) 2 provided therein. In the vicinity of the opening end portion of the via hole 2 (opening shoulder opening), the plating deposition is prioritized and the opening end portion is closed with the metal material (plating film) 8, and the metal material 8 embedded in the via hole 2. A so-called pinch-off phenomenon occurs in which a void 8a is generated inside. This phenomenon is prominent particularly when a wiring penetrating inside the semiconductor chip is formed.

  Although some improvement is possible by suppressing the plating current flowing during electrolytic plating and adjusting the additive added to the plating solution, in this case, the metal material is buried in the via hole at high speed. For example, it takes several hours to completely fill the metal material inside the via hole having a depth of 100 μm.

  The present invention has been made in view of the above-described points, and even if the recess has a high aspect ratio and a deep depth, such as a via hole, a concave portion is formed in a metal material such as copper without generating voids therein. It is an object of the present invention to provide a film forming method and a film forming apparatus which can be embedded in a high speed and surely.

  According to the first aspect of the present invention, there is provided a substrate having a recess and a conductive layer formed on a surface including the inside of the recess, and polymer insulation is performed on the surface of the conductive layer excluding the interior of the recess by an electrodeposition method. A film forming method is characterized in that a film is formed and electrolytic plating is performed on a surface of a substrate on which the polymer insulating film is formed to embed a metal material in the recess.

  When a wiring is formed by embedding a metal material only in fine recesses such as via holes and trenches provided on the surface of the substrate, as a method of covering the surface of the substrate other than the recesses with a polymer insulating film as a mask, for example, There is a method using a photoresist. In the case of this method, it is necessary to provide a resist opening in a wider area than the recess in order to prevent the recess from being shielded by the resist due to misalignment. Therefore, it is located near the opening end of the recess. Since the polymer insulating film is not provided on the surface of the substrate, the deposition of the plating film here cannot be suppressed. On the other hand, according to the present invention, the polymer insulating film can be formed by electrodeposition to cover the shoulder of the recess with the polymer insulating film, thereby serving as a mask. By suppressing the deposition of the plating film on the surface of the polymer insulating film, the metal material can be embedded in the recess only at high speed and reliably by electrolytic plating. When electrodeposition of the polymer insulating film is performed, for example, if conditions such as sufficient agitation are applied, the film may be formed even inside the recess shoulder, but for this purpose, the film is substantially formed on the recess shoulder. The conditions so that the film stays are selected.

  According to a second aspect of the present invention, the current-carrying layer is formed on the substrate by vaporizing an organic metal under an electrolytic plating method, an electroless plating method, a vacuum deposition method, a sputtering method, a CVD method, an ALD method, or atmospheric pressure. The film forming method according to claim 1, wherein the film is formed by any one of organometallic methods for forming a film.

  The method of forming the current-carrying layer when coating with a polymer insulating film by electrodeposition is by a wet process such as electrolytic plating or electroless plating, such as vacuum deposition, sputtering, CVD, or ALD. A dry process is well known, but besides this, an organometallic method of forming a metal film by introducing an organometallic vapor onto a heated substrate and thermally decomposing it can also be applied.

A third aspect of the present invention is the film forming method according to the first or second aspect, wherein the polymer insulating film is formed by electrodeposition of a cationic polymer material.
By electrodeposition, a polymer insulating film made of an anionic polymer material and a cationic polymer material can be formed. When the polymer insulating film is formed of an anionic polymer material, the current-carrying layer is used as an anode, and depending on the conditions, the current-carrying layer may be oxidized or dissolved, which may prevent stable electrodeposition. On the other hand, when the polymer insulating film is formed of a cationic polymer material, there is no such fear, and the electroplating in the next step is performed using the current-carrying layer as a cathode, so that there is continuity. preferable.

The invention according to claim 4 is the film forming method according to claim 3, wherein the cationic polymer material is a polyimide cationic polymer.
There are various types of cationic polymer materials. Among them, a polyimide-based cationic polymer generally has a high insulating property and is easily obtained with a uniform particle size. For this reason, by using a polyimide-based cationic polymer as the cationic polymer material, the polymer insulating film can be electrodeposited with good controllability.

According to a fifth aspect of the present invention, there is provided the film forming method according to any one of the first to fourth aspects, wherein the surface of the substrate on which the polymer insulating film is formed is cleaned.
In general, the electrodeposition solution and the electroplating solution are greatly different in pH, type of additive used, and the like. The electrodeposition liquid remaining on the surface of the substrate after the electrodeposition treatment is washed and removed from the surface of the substrate, so that the electrodeposition liquid is prevented from being mixed into the plating liquid. It is possible to prevent the change.

A sixth aspect of the present invention is the film forming method according to any one of the first to fifth aspects, wherein the polymer insulating film is heat-treated.
By performing the heat treatment, the polymer insulating film can be made into a continuous film, which can prevent unevenness in a metal material formed by subsequent electrolytic plating.

The invention according to claim 7 is characterized in that the metal material embedded in the recess by the electrolytic plating is copper, copper alloy, silver, or silver alloy. There is a film forming method.
Materials that have low electrical resistance and can be deposited by electrolytic plating include copper and silver. Accordingly, the metal material is preferably copper, silver, or an alloy thereof.

The invention according to claim 8 is the film forming method according to any one of claims 1 to 7, wherein a width or a diameter of the recess is 1 μm or more and 100 μm or less.
A ninth aspect of the present invention is the film forming method according to any one of the first to eighth aspects, wherein an aspect ratio of the concave portion is 1.0 or more.
If it is a shallow recessed part with an aspect ratio of 1.0 or less, a metal material can be embedded in the recessed part at high speed without using this method.

The invention according to claim 10 is an electrodeposition treatment unit for electrodepositing a polymer insulating film on the surface of the energization layer formed on the surface of the substrate including the inside of the recess, excluding the inside of the recess, and after the electrodeposition treatment A film forming apparatus comprising: an electrolytic plating unit that performs electrolytic plating on a surface of a substrate to embed a metal material in the recess; and a cleaning / drying unit that cleans and dries the substrate after electrolytic plating.
By having the electrodeposition processing unit and the electrolytic plating unit in the film forming apparatus, a series of processes can be continuously performed with the same apparatus (film forming apparatus), and productivity can be maintained high. By including a cleaning / drying unit in the film forming apparatus, the processed substrate can be taken out in a dry state, and subsequent storage of the substrate is facilitated.

  According to an eleventh aspect of the present invention, the electrodeposition treatment unit includes an electrodeposition tank that holds an electrodeposition liquid therein, and upper and lower electrodes that are disposed in the electrodeposition tank and hold the substrate horizontally with the surface facing downward. A movable substrate holder, a cathode contact provided in contact with the current-carrying layer of the substrate provided on the substrate holder and held by the substrate holder and having the current-carrying layer as a cathode, and an electrodeposition liquid in the electrodeposition tank 11. The film forming apparatus according to claim 10, further comprising an anode that is immersed and disposed horizontally.

  When the substrate is a cathode, hydrogen gas is generated on the substrate side. At that time, if the substrate is held in a so-called face-down direction, the hydrogen gas generated on the surface of the substrate excluding the recesses is relatively easily desorbed from the surface of the substrate, but is generated in the recesses of the substrate. Since the surface of the hydrogen gas faces downward, it does not easily desorb from the recess. For this reason, gas accumulates inside the recess, and this gas inhibits electrodeposition of the polymer insulating film. Thereby, the polymer insulating film which becomes an obstacle of the electroplating of the next process can be more reliably formed only on the substrate surface excluding the inside of the recess and the shoulder of the recess. It is desirable not to stir the electrodeposition liquid when forming the polymer insulating film.

  According to a twelfth aspect of the present invention, the electrolytic plating unit includes: a plating tank that holds a plating solution; and a plating solution outlet that jets the plating solution toward the surface of the substrate disposed inside the plating tank. The film forming apparatus according to claim 10, further comprising: a plating solution spray nozzle having the same.

  For example, when a metal material is embedded in a via hole (recess) having a width (diameter) of 70 μm and a depth of 100 nm, it is necessary to positively supply metal ions to the bottom of the via hole. By spraying the plating solution from the spray nozzle having the plating solution outlet toward the substrate, a fresh plating solution can be supplied to the bottom of the via hole. As the shape of the plating solution outlet, for example, a slit-like shape is preferable. Further, if the plating solution is continuously supplied at a fixed position, the consumed plating solution stays in the via hole, and the plating rate is lowered. Therefore, the plating rate can be maintained at a high speed by moving the plating solution spray nozzle to promote the replacement of the plating solution inside the via hole. The plating solution spray nozzle is not necessarily required to be a single one, and may be a nozzle group assembly in which a plurality of plating solution spray nozzles are arranged in series, or a plurality of nozzle group assemblies may be used simultaneously.

The invention according to claim 13 is the film forming apparatus according to claim 12, wherein the plating solution is a copper sulfate plating solution containing copper sulfate.
The plating solution is selected depending on the metal material to be formed. However, since the plating film is formed relatively thick by electrolytic plating, the plating solution is preferably as inexpensive as possible. A copper sulfate plating solution is used in a wide range and is suitable for low cost.

The invention according to claim 14 further comprises an electrodeposition liquid cleaning unit for cleaning and removing the electrodeposition liquid remaining on the surface of the substrate after the electrodeposition treatment. A film forming apparatus.
The electrodeposition solution remaining on the surface of the substrate after the electrodeposition treatment is washed and removed by the electrodeposition solution cleaning unit, so that generally the electrodeposition solution and the electroplating solution differ greatly in pH and the type of additive used. Mixing with each other can prevent the composition of the plating solution from changing.

The invention according to claim 15 further comprises a heat treatment unit for heat-treating the polymer insulating film electrodeposited on the surface of the current-carrying layer. is there.
By performing heat treatment in the heat treatment unit, the polymer insulating film can be made into a continuous film.

  According to the present invention, by forming a polymer insulating film on the surface of the current-carrying layer excluding the inside of the recess by electrodeposition, the shoulder to the recess can be covered with the polymer insulating film as a mask. This makes it possible to embed a metal material such as copper at high speed and surely only in the recesses without generating voids, even in recesses such as via holes with high aspect ratios and deep depths. it can.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiment, an example in which copper is used as a metal material is shown.
FIG. 2 shows an overall layout of the film forming apparatus according to the embodiment of the present invention. As shown in FIG. 2, the film forming apparatus 40 includes a load unit 41, an unload unit 42, a cleaning / drying unit 43, a load stage 44, an electrodeposition liquid cleaning unit 45, an electrodeposition processing unit 46, an electroplating unit 47, A first transfer robot 48 and a second transfer robot 49 are provided.

  In this example, the electrodeposition processing unit 46 electrodeposits a polymer insulating film 208 made of a cationic polymer material, preferably a polyimide cationic polymer, on the surface of the conductive layer 206 (FIG. 9 ( b)). By electrodeposition, a polymer insulating film made of an anionic polymer material and a cationic polymer material can be formed. However, when a polymer insulating film is formed of an anionic polymer material, the current-carrying layer will be the anode, Depending on the conditions, oxidation and dissolution of the conductive layer may occur, and stable electrodeposition may not be possible. On the other hand, when the polymer insulating film is formed of a cationic polymer material, there is no such fear, and the electroplating in the next step is performed using the current-carrying layer as a cathode, so that there is continuity. preferable. Furthermore, it is generally easy to obtain a polyimide-based cationic polymer having a high insulating property and a uniform particle size. For this reason, by using a polyimide-based cationic polymer as the cationic polymer material, the polymer insulating film can be electrodeposited with good controllability.

Therefore, in this example, the electrodeposition liquid is a polyimide colloid having a diameter of several hundreds of nanometers, and a large number of N ⁺ is present on the surface, and the colloid is dispersed in a solvent (pure water containing an organic solvent). Is used.

  As shown in FIG. 3, the electrodeposition processing unit 46 has an electrodeposition processing unit main body 11 and a substrate holder 12 for holding a substrate W such as a semiconductor wafer accommodated therein. The substrate holder 12 includes a substrate holding portion 12-1 and a shaft portion 12-2. The shaft portion 12-2 is rotatably supported on the inner wall of the cylindrical guide member 14 via bearings 15 and 15. . The guide member 14 and the substrate holder 12 can be moved up and down with a predetermined stroke by a cylinder 16 provided at the top of the electrodeposition processing unit main body 11.

  The substrate holder 12 can be rotated in the arrow A direction via the shaft portion 12-2 by a motor 18 provided in the upper upper portion of the guide member 14. Inside the substrate holder 12, a space C for housing the substrate pressing member 17 composed of the substrate pressing portion 17-1 and the shaft portion 17-2 is provided. The substrate pressing member 17 is provided with the shaft portion 12 of the substrate holder 12. -2 can be moved up and down with a predetermined stroke by a cylinder 19 provided in the upper part.

  An opening 12-1a communicating with the space C is provided below the substrate holding portion 12-1 of the substrate holder 12, and an edge portion of the substrate W is formed above the opening 12-1a as shown in FIG. Is formed on the stepped portion 12-1b. The edge of the substrate W is placed on the stepped portion 12-1b, and the upper surface of the substrate W is pressed by the substrate pressing portion 17-1 of the substrate pressing member 17, so that the edge of the substrate W becomes the substrate pressing portion 17. -1 and the stepped portion 12-1b. And the surface (lower surface) of the board | substrate W is exposed to the opening 12-1a. 4 is an enlarged view of a portion B in FIG.

  A flat electrodeposition tank 20 is provided below the substrate holding portion 12-1 of the electrodeposition processing unit body 11, that is, below the substrate W exposed in the opening 12-1 a, and a number of holes are provided below the electrodeposition tank 20. A flat electrodeposition liquid introduction chamber 22 is provided through a perforated plate 21 on which 21a is formed. Further, a collection rod 23 for collecting the electrodeposition liquid L overflowing the electrodeposition tank 20 is provided outside the electrodeposition tank 20.

The electrodeposition liquid L collected by the collection rod 23 is returned to the electrodeposition liquid tank 24 when the electrodeposition liquid is replaced or replenished. The electrodeposition liquid L in the electrodeposition liquid tank 24 is introduced horizontally from both sides of the electrodeposition tank 20 by the pump 25. The electrodeposition liquid L introduced from both sides of the electrodeposition tank 20 passes through the holes 21a of the perforated plate 21 and flows into the electrodeposition tank 20 as a vertical jet. The interval between the perforated plate 21 and the substrate W is 5 to 15 mm, and the jet of the electrodeposition liquid L that has passed through the holes 21a of the perforated plate 21 becomes a uniform jet while maintaining the vertical rise. The electrodeposition solution is stirred and homogenized. The electrodeposition liquid L that has overflowed the electrodeposition tank 20 at the time of electrodeposition liquid replacement / replenishment is collected by the collection tank 23 and flows into the electrodeposition liquid tank 24. Thereby, the electrodeposition liquid L circulates between the electrodeposition tank 20 and the electrodeposition liquid tank 24 of the electrodeposition processing unit main body 11.
Chakuekimen level L _Q electrodeposition electrodeposition tank 20 is higher only slightly ΔL lower surface level L _W of the substrate W, the entire surface of the lower surface of the substrate W is in contact with the electrodeposition solution L.

  As shown in FIG. 4, the stepped portion 12-1 b of the substrate holding portion 12-1 of the substrate holder 12 is electrically connected to the conductive layer 206 (see FIG. 9A) of the substrate W, and the conductive layer A cathode contact 27 having 206 as a cathode is provided. The cathode contact 27 is electrically connected to the brush 26 with an electric wire (not shown), and is further connected to the cathode of an external plating power source (not shown) via the brush 26. An anode 28 made of, for example, SUS is provided on the bottom of the electrodeposition tank 20 of the electrodeposition processing unit body 11 so as to face the substrate W, and this anode 28 is connected to the anode of the plating power source. At a predetermined position on the wall surface of the electrodeposition processing unit main body 11, a loading / unloading slit 29 for loading / unloading the substrate W by a substrate loading / unloading jig such as a robot arm is provided.

  In performing the electrodeposition process in the electrodeposition processing unit 46 having the above-described configuration, first, the cylinder 16 is operated, and the substrate holder 12 is moved along with the guide member 14 by a predetermined amount (the substrate W held by the substrate holder 12-1 is unloaded). And the cylinder 19 is operated to raise the substrate pressing member 17 by a predetermined amount (to a position where the substrate pressing portion 17-1 reaches the upper portion of the carry-in / out slit 29). In this state, the substrate W is carried into the space C of the substrate holder 12 by a substrate carry-in / out jig such as a robot arm, and the substrate W is placed on the stepped portion 12-1b with its surface facing downward. In this state, the cylinder 19 is operated and lowered until the lower surface of the substrate pressing portion 17-1 contacts the upper surface of the substrate W, and the edge portion of the substrate W is interposed between the substrate pressing portion 17-1 and the stepped portion 12-1b. Pinch.

In this state, by operating the cylinder 16, only the lower position the ΔL than before (electrostatic Chakuekimen level L _Q of the substrate holder 12 is a lower surface of the guide member 14 together with the substrate W in contact with the electrodeposition solution L electrodeposition tank 20 To lower). At this time, if necessary, the motor 18 is activated and lowered while rotating the substrate holder 12 and the substrate W at a low speed. The electrodeposition tank 20 is filled with the electrodeposition liquid L. When a predetermined voltage is applied from the plating power source between the anode 28 and the cathode contact 27 in this state, a current flows from the anode 28 to the conductive layer 206 of the substrate W as a cathode, as shown in FIG. A polymer insulating film 208 is formed on the surface (lower surface) of the conductive layer 206 of the substrate W.

As described below, during the electrolytic treatment, the rotation of the substrate W is stopped, the substrate W is stopped, and the electrodeposition liquid is not supplied into the electrodeposition tank 20, so that the electrodeposition liquid is not stirred. Is preferred.
Actuating the cylinder 16 when the electrodeposition process is completed, the substrate holder 12 and the substrate W is raised, when the lower surface of the substrate holding portion 12-1 becomes above the electrodeposition Chakuekimen level L _Q, rotate the motor 18 at high speed The electrodeposition liquid adhering to the lower surface of the substrate and the lower surface of the substrate holding part 12-1 is shaken off by centrifugal force. When the electrodeposition liquid is completely shaken off, the substrate W is raised to the position of the carry-in / out slit 29, and when the cylinder 19 is operated to raise the substrate pressing portion 17-1, the substrate W is released and the substrate holding portion 12 is released. -1 stage 12-1b. In this state, a substrate carry-in / out jig such as a robot arm is made to enter the space C of the substrate holder 12 through the carry-in / out slit 29, and the substrate W is picked up and carried out to the outside.

  FIG. 5 is a longitudinal sectional view showing an outline of the electrolytic plating unit 47, and FIG. 6 is a plan view showing the arrangement of the substrate holder, anode and plating solution spray nozzle in the plating tank. The electrolytic plating unit 47 includes a plating tank 111 that stores a plating solution Q therein, and an overflow tank 113 that stores a plating solution Q that overflows the upper end of the overflow weir 112 of the plating tank 111. Inside the plating tank 111, the substrate W and the anode 115, which are immersed in the plating solution Q and are held by the substrate holder 114, are arranged perpendicularly to each other with a predetermined interval therebetween. A plating solution spray nozzle 116 for ejecting the plating solution Q is disposed vertically. The distance between the tip of the plating solution injection nozzle 116 and the surface of the substrate W is, for example, 1 to 30 mm.

  The electrolytic plating unit 47 is provided with a plurality (two in this example) of plating solution injection nozzles 116, and the upper ends thereof are fixed to the shaft 117 at a predetermined interval. A rack 118 is provided on the lower surface of the shaft 117, and the shaft 117 reciprocates in the direction of arrow A by rotating the pinion 119 meshing with the rack 118 forward and backward by the motor 120, and the plating solution injection nozzle 116 is also in the same direction. Reciprocate. The plating solution spray nozzle 116 may be single or a plurality of sets of the plating solution spray nozzles 116 may be provided.

  Although not shown, the substrate holder 114 is configured to hold the substrate W by watertightly sealing the peripheral edge of the substrate W, and the substrate holder 114 includes a surface of the substrate W held by the substrate holder 114. A cathode contact is provided in contact with the peripheral portion of the energization layer 206 (see FIG. 9A) provided on the substrate to make the energization layer 206 a cathode.

  7A is a plan view of the plating solution injection nozzle 116, FIG. 7B is a front view of the plating solution injection nozzle 116, and FIG. 7C is a cross-sectional view taken along line BB in FIG. 7B. It is. The plating solution spray nozzle 116 is long and has a substantially rectangular shape with a cross section formed on one side thereof, and a plating solution supply hole 116a is formed in the center portion along the length direction. A plurality of slit-shaped plating solution jets 116c communicating with the plating solution supply hole 116a are arranged in series at the top of the convex portion 116b. By supplying the plating solution to the plating solution supply hole 116a at a predetermined pressure, a strip-shaped (flat plate) plating solution corresponding to the shape is ejected from the plating solution outlet 116c.

  Each plating solution injection nozzle 116 is connected to a branch pipe (plating solution supply pipe) 122 branched from a flow manifold 121 serving as a flow distribution unit that distributes the flow rate of the plating solution, and the flow manifold (flow distribution unit) 121 is The flow rate / pressure gauge 124 is connected via a flexible pipe (plating solution supply pipe) 123. The flow rate / pressure gauge 124 is connected to the discharge port of the pump 125 via the pipe 126a, and the suction port of the pump 125 is connected to the plating solution discharge port of the overflow tank 113 via the pipe 126b. . The plating solution Q discharged to the overflow tank 113 by the pump 125 is supplied to each plating solution injection nozzle 116 through the pipes 126a and 126b, the flow rate / pressure gauge 124, the flexible pipe 123, the flow rate manifold 121 and the branch pipe 122, and is plated. It is sprayed toward the substrate W from the slit-like plating solution ejection port 116 c of the liquid ejection nozzle 116. After filling the plating tank 111, the plating solution Q overflows the upper end of the overflow weir 112 and flows into the overflow tank 113.

  A DC plating power supply 127 is connected to the substrate holder 114 and the anode 115, and a predetermined DC voltage is applied from the plating power supply 127 between the conductive layer of the substrate W held by the substrate holder 114 and the anode 115. A plating current flows from the anode 115 to the substrate W. As a result, a metal material (plating film) 210 is formed on the surface of the conductive layer 206 in the recess 202 of the substrate W, as shown in FIG. During the plating process of the substrate W, each plating solution injection nozzle 116 attached to the shaft 117 is moved in a predetermined stroke parallel to the substrate W by a nozzle moving mechanism including a rack 118, a pinion 119, and a motor 120. While reciprocating, the plating solution is sprayed from the plating solution outlet 116 c toward the surface of the substrate W. Thereby, each plating solution injection nozzle 116 has a function of supplying the plating solution uniformly to the surface of the substrate W and a function of supplying the plating solution Q into the plating tank 111.

  The ejection speed of the plating solutions q1, q2, q3... Ejected from the plating solution ejection port 116c of the plating solution ejection nozzle 116 is determined by the flow rate and pressure of the plating solution Q supplied from the pump 125 to the flow rate manifold 121. Accordingly, by feeding back the flow rate / pressure detected by the flow rate / pressure gauge 124 to the pump 125, the ejection speed of the plating solutions q1, q2, q3,... Ejected from the plating solution ejection port 116c of the plating solution ejection nozzle 116, and The flow rate can be controlled. The flow manifold 121 distributes the plating solution flow rate to each plating solution injection nozzle 116 in consideration of the flow conductance of the plating solution Q.

  The length of the flexible pipe 123 is set to such a length that the shaft 117, that is, the plating solution injection nozzle 116 does not hinder the reciprocating movement with a predetermined stroke and can smoothly follow the movement of the plating solution injection nozzle 116. . In the above example, the combination of the rack 118 and the pinion 119 is used as the nozzle movement mechanism for reciprocating the shaft 117. However, the nozzle movement mechanism is not limited to this, and the nozzle movement including the rack and the worm is performed. Any drive mechanism that can reciprocate the shaft 117 with a predetermined stroke, such as a mechanism or a drive mechanism including a linear slider, may be used.

  The plating solution injection nozzle 116 is not limited to a plurality of slit-like plating solution outlets 116c arranged in series as shown in FIG. 7, but a single long slit as shown in FIG. A configuration in which a plating solution ejection port 116d is provided may be used. 8A is a plan view of the plating solution injection nozzle 116 having a single long slit-like plating solution outlet 116d, and FIG. 8B is a single long slit-like plating solution outlet. It is a front view of the plating solution injection nozzle 116 which has 116d. The slit width dimensions of the slit-shaped plating solution outlets 116c and 116d are, for example, 0.05 to 1.0 mm. In the above-described example, the plating solution injection nozzle 116 has a substantially rectangular cross-sectional shape, but is not limited thereto, and is not limited to this. The cross-sectional shape is not particularly limited as long as it has a plating solution outlet and can eject a belt-like (flat plate) plating solution from the plating solution outlet.

  Further, the flow rate of the plating solution ejected from the plating solution jet nozzles 116 c and 116 d of each plating solution jet nozzle 116 and the pressure in each plating solution jet nozzle 116 from the flow rate and pressure of the plating solution detected by the flow rate / pressure gauge 124. And a monitor unit (not shown) for monitoring at least one of the flow rate of the plating solution to be sprayed and the pressure in the plating solution spray nozzle 116 is provided. It is possible to constantly monitor at least one of the pressures in order to maintain and adjust the plating process to an optimum state.

An example in which the copper wiring is formed using the film forming apparatus configured as described above will be described with reference to FIG.
First, as shown in FIG. 9A, an insulating film (interlayer insulating film) 200 made of SiO ₂ or the like is formed on the upper surface by, for example, PVD, CVD, or wet coating, and the insulating film 200 has, for example, A recess 202 such as a trench or a via hole is formed by RIE, CDE, sputter etching, or wet etching, a barrier layer 204 is formed on the insulating film 200 including the surface of the recess 202, and a seed as a conductive layer is formed on the barrier layer 204. A substrate W on which each of the layers 206 is formed is prepared. Then, the substrate W is stored in the cassette and carried into the load unit 41, and at the same time, an empty cassette is carried into the unload unit 42.

The size of the opening of the recess 202, that is, the diameter or width S is 1 μm or more and 100 μm or less, and the recess 202 has an aspect ratio of 1 or more. The present invention is particularly effective for embedding a metal material in the concave portion 202 having such a shape at high speed and reliably.
The conductive layer (seed layer) 206 is generally formed by a wet process such as an electrolytic plating method or an electroless plating method, or a dry process such as a vacuum deposition method, a sputtering method, a CVD method, or an ALD method. Alternatively, it may be formed by an organometallic method in which a metal film is formed by introducing an organometallic vapor onto a heated substrate and thermally decomposing it.

  In this example, the substrate W before wiring formation is carried into the load unit 41, and the substrate W after wiring formation is carried out from the unload unit 42, but one load / unload is shown. After the substrate W is loaded from a certain cassette and the wiring formation process is performed using the unit, the substrate W on which the wiring is formed may be returned to the same cassette.

  Next, the substrates W are taken out one by one from the cassette of the load unit 41 by the first transfer robot 48, and transferred to the electrodeposition processing unit 46 by the second transfer robot 49 via the load stage 44. In this electrodeposition processing unit 46, as shown in FIG. 9B, a polymer insulating film 208 made of, for example, a polyimide-based cationic polymer is formed on the surface of the energizing layer 206 excluding the concave portion 202. This polymer insulating film 208 plays a role as a mask in the following electroplating, and the polymer insulating film 208 is formed by electrodeposition to form the polymer insulating film up to the shoulder of the recess 202. 208 can be coated.

That is, as shown in the following formula, water is electrolyzed on the conductive layer (cathode) 206 side to generate hydrogen, and the pH in the vicinity of the conductive layer (cathode) 206 becomes alkaline.
2H ₂ O + 2e → H ₂ + 2OH ⁻
Numerous N ⁺ are present on the surface of the polyimide colloid dispersed in the electrodeposition solution. For this reason, the N ⁺ and OH ⁻ are neutralized as in the following formula, and the polyimide is deposited on the surface of the conductive layer (cathode) 206 and adheres.
-N ^{+ +} OH ^- → -NOH

  As described above, when the conductive layer 206 of the substrate W is used as a cathode, hydrogen gas is generated on the substrate side. At that time, when the substrate W is held in a so-called face-down direction with the surface facing downward, the hydrogen gas generated on the surface of the substrate W excluding the concave portion 202 is relatively easily desorbed from the surface of the substrate W. The hydrogen gas generated in the recess 202 is not easily detached from the recess 202 because the surface is directed downward. For this reason, air bubbles accumulate inside the recess 202, and the air bubbles impede electrodeposition of the polymer insulating film 208. As a result, the polymer insulating film 208 that obstructs electrolytic plating in the next process can be more reliably formed only on the surface of the substrate W excluding the inside of the recess 202 and the shoulder opening of the recess 202.

  Here, while rotating the substrate W and stirring the electrodeposition liquid, the bottom (Bottom) and middle (Middle) of the recess 202 when the polymer insulating film 208 is formed on the surface of the energization layer (seed layer) 206. ), And the time variation of the film thickness of the polymer insulating film 208 other than the recess (Top) and the polymer insulating film 208 on the surface of the conductive layer 206 without stirring the electrodeposition liquid while the substrate W is stopped. FIG. 10 shows the results of investigating the film thickness and time variation of the polymer insulating film 208 at the bottom (Bottom) and middle (Middle) of the recess 202 and when not forming the recess (Top).

  From FIG. 10, for example, within 100 seconds, when the electrodeposition treatment is performed while stirring the electrodeposition solution, the film thickness of the polymer insulating film 208 formed particularly on the bottom of the recess 202 increases with time. Therefore, it can be seen that it is preferable to perform the electrodeposition treatment without stirring the electrodeposition liquid in order to prevent the polymer insulating film 208 from being formed on the bottom of the recess 202. This is presumably because the OH concentration at the bottom of the recess 202 increases as the volume of the recess 202 decreases.

By performing the electrodeposition process without stirring the electrodeposition liquid, the polymer insulating film 208 having a larger film thickness is formed on the surface other than the recess 202 and the opening end of the recess 202 compared to the inside of the recess 202 for diffusion control. A film can be formed. By using a low polyimide concentration as the electrodeposition liquid, the number of polyimide particles present in the recesses 202 is reduced, and the current density applied during the electrodeposition process is increased to increase the H ₂ gas. The amount of generated gas can be increased, and gas can easily accumulate in the recess 202. For this reason, in order to reliably form the polymer insulating film 208 on the surface other than the concave portion 202 and the opening end portion of the concave portion 202, an electrodeposition solution having a low polyimide concentration is used. It is preferable to increase the current density to be applied. The concentration of the electrodeposition solution used is preferably 6% or less. This current density is, for example, 0.03 to 0.1 mA / cm ² (constant current method).

  After the electrodeposition process is completed, the substrate W is pulled up from the electrodeposition solution and rotated, and the electrodeposition solution adhering to the lower surface of the substrate W and the lower surface of the substrate holding part 12-1 is shaken off by centrifugal force. Thereafter, the substrate on which the electrodeposition liquid has been shaken off is transported to the electrodeposition liquid cleaning unit 45 by the second transport robot 49. In this electrodeposition liquid cleaning unit 45, the substrate W is held with the surface facing upward, pure water or pure water containing an organic solvent is supplied to the surface (upper surface) of the substrate, and the electrodeposition remaining on the surface of the substrate W Remove the liquid. Next, for example, 90 ° C. dried air is blown toward the substrate to dry the substrate.

  In general, the electrodeposition solution and the electroplating solution are greatly different in pH, type of additive used, and the like. The electrodeposition liquid remaining on the surface of the substrate after the electrodeposition treatment is washed and removed from the surface of the substrate, so that the electrodeposition liquid is prevented from being mixed into the plating liquid. It is possible to prevent the change.

  The second transfer robot 49 receives the dried substrate and transfers it to the electroplating unit 47. In this electrolytic plating unit 47, the substrate W is held and lowered in the vertical direction by the substrate holder 114 and immersed in the plating solution Q in the plating tank 111. The plating solution is ejected from the plating solution ejection port 116 c of the plating solution ejection nozzle 116 toward the surface of the substrate W while applying a predetermined voltage between the energization layer (seed layer) 206 of the substrate W and the anode 115. As a result, as shown in FIG. 9C, a metal material 210 made of copper is formed on the surface of the energization layer (seed layer) 206 located in the recess 202, and the copper only into the recess 202 is formed. Embedding. Then, after the end of plating, the application of voltage between the conductive layer 206 of the substrate W and the anode 115 is stopped, the substrate W is pulled out of the plating solution, and rotated at a high speed to drain the plating solution.

  At the time of this plating, the surface of the energization layer 206 excluding the recesses 202 is covered with a polymer insulating film 208 that serves as a mask. For this reason, the surface of the polymer insulating film 208 is coated with a metal material (plating film) 210. As a result, the metal material 210 is deposited only inside the recess 202.

  Thus, by spraying the plating solution from the plating solution spray nozzle 116 toward the substrate W, a fresh plating solution can be supplied to the bottom of the recess 202. If the plating solution is continuously supplied at a fixed position, the consumed plating solution stays in the recess 202, and the plating rate is lowered. Therefore, the plating rate can be maintained at a high speed by moving the plating solution injection nozzle 116 to promote the replacement of the plating solution existing inside the recess 202.

  The plating solution is selected depending on the metal material to be formed. However, since the plating film is formed relatively thick by electrolytic plating, the plating solution is preferably as inexpensive as possible. If it is a copper sulfate plating solution, it is widely used and its cost is low. For this reason, it is preferable to use a copper sulfate plating solution containing copper sulfate as the plating solution.

  The second transfer robot 49 receives the substrate W from the electrolytic plating unit 47 and transfers it to the load stage 44. The first transfer robot 48 receives the substrate from the load stage 44 and transfers it to the cleaning / drying unit 43. Then, after the substrate is cleaned and spin-dried by the cleaning / drying unit 43, the dried substrate is carried into the cassette of the unload unit 42 by the first transport robot 48.

  Since this film forming apparatus includes the electrodeposition processing unit 46 and the electrolytic plating unit 47, it is possible to continuously perform a series of processes with the same apparatus (film forming apparatus) and maintain high productivity. Furthermore, since the film forming apparatus also includes the cleaning / drying unit 43, the processed substrate can be taken out in a dry state, and subsequent storage of the substrate is facilitated.

  FIG. 11 is a plan view showing the overall configuration of another embodiment of the present invention. In this film forming apparatus, a first polishing unit 80a and a second polishing unit 80b are arranged opposite to each other on one end side of a space on a floor having a rectangular shape as a whole, and a substrate such as a semiconductor wafer is provided on the other end side. A load / unload unit 82 for placing substrate cassettes 81a and 81b for storing W is disposed, and a control unit 92 is provided adjacent to the load / unload unit 82. Two transfer robots 83a and 83b are arranged on a line connecting the polishing units 80a and 80b and the load / unload unit 82.

  Further, an electrodeposition processing unit 46, an electrodeposition liquid cleaning unit 45, a heat treatment unit 84, and an electrolytic plating unit 47 are disposed on one side along the transfer line, and on the other side, a film thickness inspection unit 85, a cleaning / cleaning unit. A drying unit 43, an electroless plating unit 88 for forming a protective film, and a post-cleaning unit 89 including a roll sponge are arranged. On the transfer line side of the polishing units 80a and 80b, pushers 90 and 90 that are movable up and down to transfer the substrate W to and from the polishing units 80a and 80b are provided.

  In this film forming apparatus, in the same manner as described above, as shown in FIG. 9B, a polymer insulating film 208 is formed on the surface excluding the concave portion 202 of the conductive layer 206 by the electrodeposition processing unit 46. Then, the electrodeposition liquid cleaning unit 45 cleans and removes the electrodeposition liquid remaining on the substrate, and dries the substrate W. Then, the substrate W is transported to the heat treatment unit 84, where the polymer insulating film 208 is heat treated (annealed). In this way, by heat treatment, the polymer insulating film 208 is used as a continuous film to improve the adhesion with the current-carrying layer 206, so that unevenness does not occur in the metal material formed by subsequent electrolytic plating. can do.

The substrate W after the heat treatment is transferred to the electroplating unit 47, and here, in the same manner as described above, a metal material (on the surface of the conductive layer 206 is formed in the concave portion 202 of the substrate W as shown in FIG. 9C. (Plating film) 210 is formed, and then the surface of the substrate W is cleaned by the cleaning / drying unit 43 to dry the substrate.
Next, the substrate W is transported to the film thickness inspection unit 85, where the film thickness of the metal material 210 is measured, and the substrate W is reversed by a reversing machine as necessary. Thereafter, the substrate W is transferred onto the pusher 90 of the polishing unit 80a or 80b by the transfer robots 83a and 83b.

  In the polishing unit 80a or 80b, polishing is performed by supplying a polishing liquid while pressing the polishing surface of the substrate W against the polishing table. Then, for example, when an end point is detected by a monitor for inspecting the finish of the substrate W, the polishing is finished, and the substrate W after the polishing is returned to the pusher 90 and once cleaned with pure water spray. Next, the substrate W is transported to the post-cleaning unit 89 by the transport robot 83b and cleaned with, for example, a roll sponge. Thus, as shown in FIG. 12A, the excess metal material 210, the polymer insulating film 208, the conductive layer 206, and the barrier layer 204 on the insulating film 200 are polished and removed, and the inside of the insulating film 200 is removed. A wiring 212 made of a conductive layer (seed layer) 206 and a metal material (copper) 210 is formed.

Next, the substrate W is transported to an electroless plating unit 88, where, for example, after pretreatment such as application of a Pd catalyst or removal of an oxide film on an exposed surface is performed as necessary, the electroless plating is performed. Apply processing. Thus, as shown in FIG. 12B, a protective film (plating film) 214 made of, for example, a CoWP alloy film is selectively formed on the surface of the exposed wiring 212 after polishing to protect the wiring 212. The thickness of the protective film 214 is about 0.5 to 500 nm, preferably about 1 to 200 nm, and more preferably about 10 to 100 nm. Then, the substrate W on which the protective film 214 is formed is cleaned and dried by the cleaning / drying unit 43, and then returned to the substrate cassette 81a or 81b of the load / unload unit 82.
In the above example, an example of the device layout is shown, but the present invention is not limited to this. The number of cleaning / drying units may be increased to improve the throughput.

  In the above example, copper is used as the metal material, but copper alloy, silver or silver alloy may be used in addition to copper. In addition, although an example using a CoWP alloy film as the protective film 214 is shown, in addition to a CoWP alloy, a Co simple substance, a CoWB alloy, a CoP alloy, or a Co alloy such as CoB may be used. A simple substance or a Ni alloy such as a NiWP alloy, a NiWB alloy, a NiP alloy, or a NiB alloy may be used.

It is a figure which shows the outline | summary when a metal material is embedded in the inside of a via hole (concave part) with a high aspect ratio and deep depth. 1 is an overall layout diagram of a film forming apparatus according to an embodiment of the present invention. It is sectional drawing which shows the electrodeposition processing unit with which the film-forming apparatus shown in FIG. 2 is equipped. It is the B section enlarged view of FIG. It is sectional drawing which shows the outline | summary of the electroplating unit with which the film-forming apparatus shown in FIG. 2 is equipped. It is a top view which shows the board | substrate holder in the plating tank of the electrolytic plating unit shown in FIG. 5, an anode, and a plating solution injection nozzle. (A) is a top view of the plating solution injection nozzle 116, (b) is a front view of the plating solution injection nozzle, and (c) is a BB sectional view of (b). (A) is a top view of the other plating solution injection nozzle 116, (b) is a front view of another plating solution injection nozzle. It is a figure which shows the example which forms a copper wiring using the film-forming apparatus shown in FIG. 2 in order of a process. The thickness of the polymer insulating film at the bottom and middle of the recess when the polymer insulating film is formed on the surface of the current-carrying layer while stirring the electrodeposition solution. Changes in time and polymer insulation at the bottom and middle of the recess when a polymer insulating film is deposited on the surface of the current-carrying layer without stirring the electrodeposition solution, and at the top of the recess It is a graph which shows the result of having investigated the film thickness of a film | membrane, and the time change. It is a plane arrangement view of a film forming apparatus according to another embodiment of the present invention. FIG. 12 is a diagram illustrating a sequence of processes after embedding a metal material of an example of forming a copper wiring by using the film forming apparatus illustrated in FIG. 11.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Electrodeposition processing unit main body 12 Substrate holder 17 Substrate pressing member 20 Electrodeposition tank 21 Perforated plate 22 Electrodeposition liquid introduction chamber 23 Collection rod 24 Electrodeposition liquid tank 27 Cathode contact 28 Anode 40 Deposition apparatus 41 Load part 42 Unload Unit 43 Cleaning / drying unit 44 Load stage 45 Electrodeposition liquid cleaning unit 46 Electrodeposition processing unit 47 Electrolytic plating units 80a, 80b Polishing unit 82 Load / unload unit 84 Heat treatment unit 85 Film thickness inspection unit 88 Electroless plating unit 89 Cleaning unit 92 Control unit 111 Plating tank 113 Overflow tank 114 Substrate holder 115 Anode 116 Plating solution injection nozzles 116c, 116d Plating solution outlet 118 Rack 119 Pinion 121 Flow manifold 122 Branch pipe 123 Flexible pipe 124 Flow rate / pressure Force meter 127 Plating power source 200 Insulating film 202 Recessed portion (via hole)
204 Barrier layer 206 Conducting layer (seed layer)
208 Polymer insulating film 210 Metal material 212 Wiring 214 Protective film

Claims (15)

Prepare a substrate having a recess and a conductive layer formed on the surface including the inside of the recess,
Forming a polymer insulating film on the surface of the current-carrying layer excluding the inside of the recess by electrodeposition;
A film forming method comprising performing electrolytic plating on a surface of a substrate on which the polymer insulating film is formed to embed a metal material in the recess.   Any one of an electroplating method, an electroless plating method, a vacuum deposition method, a sputtering method, a CVD method, an ALD method, and an organic metal method for vaporizing an organic metal under normal pressure to form a metal film on the substrate. The film forming method according to claim 1, wherein   The film forming method according to claim 1, wherein the polymer insulating film is formed by electrodeposition of a cationic polymer material.   The film forming method according to claim 3, wherein the cationic polymer material is a polyimide cationic polymer.   5. The film forming method according to claim 1, wherein a surface of the substrate on which the polymer insulating film is formed is cleaned.   The film forming method according to claim 1, wherein the polymer insulating film is heat-treated.   The film forming method according to claim 1, wherein the metal material embedded in the recess by the electrolytic plating is copper, a copper alloy, silver, or a silver alloy.   The film forming method according to claim 1, wherein a width or a diameter of the recess is 1 μm or more and 100 μm or less.   The film forming method according to claim 1, wherein an aspect ratio of the concave portion is 1.0 or more. An electrodeposition treatment unit for electrodepositing a polymer insulating film on the surface of the energization layer formed on the surface of the substrate including the inside of the recess, excluding the inside of the recess;
An electrolytic plating unit that performs electrolytic plating on the surface of the substrate after the electrodeposition treatment and embeds a metal material in the recess;
A film forming apparatus having a cleaning / drying unit for cleaning and drying a substrate after electrolytic plating. The electrodeposition processing unit is
An electrodeposition tank for holding an electrodeposition liquid inside;
A substrate holder that is arranged in the electrodeposition tank and that can move up and down to hold the substrate horizontally with the surface facing downward;
A cathode contact provided in the substrate holder and in contact with the current-carrying layer of the substrate held by the substrate holder and having the current-carrying layer as a cathode;
The film forming apparatus according to claim 10, further comprising an anode that is immersed horizontally in an electrodeposition solution in the electrodeposition tank and disposed horizontally. The electrolytic plating unit is
A plating tank for holding a plating solution;
12. The film forming apparatus according to claim 10, further comprising a plating solution injection nozzle having a plating solution outlet for injecting a plating solution toward the surface of the substrate disposed inside the plating tank.   The film forming apparatus according to claim 12, wherein the plating solution is a copper sulfate plating solution containing copper sulfate.   The film forming apparatus according to claim 10, further comprising an electrodeposition liquid cleaning unit that cleans and removes the electrodeposition liquid remaining on the surface of the substrate after the electrodeposition treatment.   15. The film forming apparatus according to claim 10, further comprising a heat treatment unit for heat-treating the polymer insulating film electrodeposited on the surface of the energization layer.

Images