JP2006037140A - Plating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a plating device where the decomposition of an additive, particularly, an accelerator which exerts influence on burying properties can be sufficiently suppressed without using a complicated structure. <P>SOLUTION: The plating device comprises: a plating tank charged with a plating liquid to which an accelerator is added; an anode composed of phosphorous-containing copper; a supporting part for supporting the substrate to be plated as a cathode; a heating means for heating the plating liquid in the vicinity of the anode; and a cooling means for cooling the plating liquid made to flow from the vicinity of the anode to the vicinity of the cathode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a plating apparatus for performing metal plating such as copper plating on a substrate to be plated such as a semiconductor wafer.

  A plating method is used to perform metal plating such as copper plating on a substrate to be plated such as a semiconductor wafer. FIG. 8 shows the Cu embedded wiring manufactured by using the plating method.

  This Cu embedded wiring is manufactured as follows. First, the lower layer electrode 82 is formed on the semiconductor substrate 81. Next, a liner layer 83 and an interlayer insulating film 84 are formed on the semiconductor substrate 81. The interlayer insulating film 84 and liner layer 83 are dry etched to form a trench portion. Then, a TaN barrier metal layer 85, a Ta barrier metal layer 86, and a seed Cu layer 87 are sequentially formed on the entire surface. Further, a Cu film 88 is formed on the entire surface by a plating method. Thereafter, the Cu film 88 on the interlayer insulating film 84 is polished by CMP.

  Here, an accelerator, a suppressor, and a leveler are added to the plating solution as additives. The accelerator is made of an organic sulfur compound containing, for example, mercapdo, disulfide, etc., and is also called a brightener. It is adsorbed on the entire plating surface to improve gloss and embedding, and a void 89 is formed in the Cu film 88. prevent. Moreover, a suppressor consists of polyol ether containing glycols, such as polyethylene glycol and polypropylene glycol, for example, and is also called an inhibitor, and it adsorbs to the whole plating surface and ensures uniform electrodeposition. The leveler is a nitrogen organic compound containing, for example, an amine and is also called a smoothing agent. When the electric field is generated, the leveler is adsorbed on a portion where the electric field strength of the cathode reaction is large to suppress the precipitation reaction and reduce overgrowth. .

  In addition, phosphorus-containing copper containing phosphorus is used as an anode for stabilization. When used as it is, a disproportionation reaction in which monovalent copper becomes divalent copper and zero-valent copper occurs on the surface of the anode in contact with the plating solution, and the decomposition of the additive in the plating solution is promoted. In particular, since the decomposition of the accelerator is remarkable, the embedding property is deteriorated, and a void 89 is formed in the Cu film 88. Therefore, it is necessary not only to regularly replenish expensive additives, but also to drain the plating solution containing the additives to replenish the new solution in order to discharge the decomposition products in the plating solution. This is a cause of cost increase.

  In order to suppress the decomposition of the additive, a plating apparatus is conventionally used in which a voltage is applied between the cathode and the anode to form an oxide film containing phosphorus or the like called a black film on the anode surface. However, the black film alone cannot sufficiently suppress the decomposition of the additive. Therefore, a plating apparatus that separates the plating solution in the vicinity of the anode and the cathode using an ion exchange membrane or a porous neutral diaphragm has been proposed (for example, see Patent Document 1).

JP 2000-319797 A

  However, this conventional plating apparatus has a complicated structure and has a problem in stability, and it is necessary to manage the plating solutions near the anode and the cathode.

  The present invention has been made to solve the above-described problems, and its purpose is to sufficiently suppress decomposition of additives, particularly accelerators that affect embedding without using a complicated structure. The plating apparatus which can be obtained is obtained.

  The plating apparatus according to the present invention heats a plating bath for containing a plating solution to which an accelerator is added, an anode made of phosphorous copper, a support portion that supports a substrate to be plated that becomes a cathode, and a plating solution in the vicinity of the anode. Heating means for cooling, and cooling means for cooling the plating solution flowing from the vicinity of the anode to the vicinity of the cathode. Other features of the present invention will become apparent below.

  According to the present invention, decomposition of an additive, particularly an accelerator that affects embedding properties can be sufficiently suppressed without using a complicated structure. Thereby, embedding property can be ensured.

Embodiment 1 FIG.
1 is a cross-sectional view showing a plating apparatus according to Embodiment 1 of the present invention. A plating solution 12 containing a copper sulfate solution as a main component is placed in a cylindrical plating tank 11. However, an accelerator, a suppressor, and a leveler are added to the plating solution 12 as additives.

  And in the plating tank 11, the support part 15 which supports the anode 13 which consists of phosphorous copper, and the to-be-plated board | substrate 14 used as a cathode is provided. The anode 13 is fed by an anode feeding point 16, and the substrate to be plated 14 is fed by a cathode feeding point 17. Note that the substrate 14 to be plated is supported to be inclined with respect to the anode 13 in order to suppress trapping of bubbles on the surface of the substrate 14 to be plated.

  Further, a nozzle 18 is provided for supplying a plating solution into the plating tank 11. FIG. 2 is a bottom view (a) and a sectional view (b) showing the nozzle 18. As shown in the drawing, the nozzle 18 branches in three directions, and a plurality of outlets 25 for discharging the plating solution are provided below the branched branches. A plating solution is blown out from the nozzle 18 toward the membrane filter 19.

  The membrane filter 19 is a filter provided in order to prevent floating substances generated by peeling of a black film (not shown) formed on the surface of the anode 13 from adhering to the substrate 14 to be plated.

  The plating solution blown downward from the nozzle 18 passes through the membrane filter 19 and contacts the side wall of the plating tank 11 and the anode 13. As a result, the flow of the plating solution changes to an upward flow. Then, the plating solution again passes through the membrane filter 19 and further passes through the rectifying plate 20 and reaches the substrate 14 to be plated. The current plate 20 is provided in order to make the flow of the plating solution uniform on the surface of the substrate 14 to be plated and to ensure the uniformity of the plating film thickness.

  Then, after reaching the substrate 14 to be plated, the plating solution is pumped out to the tank 21 outside the plating tank 11. This tank 21 can store 150 liters of plating solution. The plating solution in the tank 21 is pumped out by the pump 23 and supplied to the nozzle 18 via the filter 24.

  Furthermore, the plating apparatus according to Embodiment 1 has the following configuration. FIG. 3 is a cross-sectional view showing the anode used in the first embodiment. As shown, a ceramic heater 26 is attached to the anode 13 as a heating means. The ceramic heater 26 heats the plating solution in the vicinity of the anode 13. Here, when the ceramic heater 26 is mounted inside the anode 13, it is not necessary to consider the acid resistance of the ceramic heater 26. On the other hand, when the ceramic heater 26 is attached to the outside of the anode 13, it is necessary to coat the surface of the ceramic heater 26 with Teflon (registered trademark).

  4 is a top view (a) and a cross-sectional view (b) showing the current plate used in the first embodiment. The rectifying plate 20 has a plurality of openings 27 that are uniformly provided concentrically when viewed from above. Then, the plating solution flows from the vicinity of the anode 13 to the vicinity of the cathode through the opening 27. However, the rectifying plate 20 is a cooling means for cooling the plating solution flowing from the vicinity of the anode 13 to the vicinity of the cathode by introducing cooling water therein.

  Here, FIG. 5 is a diagram showing the temperature dependence of the concentration change of the additive. As shown in FIG. 5A, the higher the temperature of the plating solution, the more the accelerator is decomposed. When the plating solution is heated to a high temperature, as shown in FIGS. 5B and 5C, the suppressor and the leveler tend to decrease. However, the reduction amount of the suppressor and the leveler is small, and the effect of suppressing the decomposition of the accelerator becomes larger.

  Therefore, the temperature of the plating solution in the vicinity of the anode 13 is set to 25 to 45 ° C. by the ceramic heater 26 as heating means. Thus, by setting it as 25 degreeC or more, as shown to Fig.5 (a), decomposition | disassembly of an accelerator can fully be suppressed. Moreover, it can prevent that the temperature of a cathode vicinity becomes high too much by setting it as 45 degrees C or less. More preferably, the temperature of the plating solution in the vicinity of the anode 13 is set to 30 to 40 ° C.

  Further, the plating solution flowing from the vicinity of the anode 13 to the vicinity of the cathode is cooled by the rectifying plate 20 as a cooling means, and the temperature of the plating solution in the vicinity of the cathode is set to 20 to 30 ° C. Thereby, when the plating liquid which has a copper sulfate solution as a main component is used, a plating reaction can be performed appropriately.

  As described above, in the plating apparatus according to Embodiment 1, a temperature gradient is applied to the plating solution in the plating tank so that the temperature of the plating solution near the anode 13 is higher than that near the cathode. More preferably, the temperature of the plating solution in the vicinity of the anode 13 is set higher by 5 ° C. or more than that in the vicinity of the cathode. Thereby, decomposition | disassembly of the accelerator which affects an additive, especially embedding property can fully be suppressed, without using a complicated structure.

Embodiment 2. FIG.
FIG. 6 is a sectional view showing a plating apparatus according to Embodiment 2 of the present invention. Constituent elements similar to those in FIG.

  In the plating apparatus according to the second embodiment, two nozzles, an anode nozzle 28 and a cathode nozzle 29, are provided. As shown in FIG. 7, the cathode nozzle 29 is provided with a blowing port 33 on the upper side, and supplies a plating solution in the vicinity of the cathode. On the other hand, the anode nozzle 28 supplies a plating solution to the vicinity of the anode 13.

  Further, in order to cool the plating solution in the tank 21 to 20 to 30 ° C., cooling means 30 for circulating cooling water in the tank 21 is provided. The pump 23 pumps the plating solution from the tank 21 and supplies it to the anode nozzle 28 and the cathode nozzle 29. Thus, since the cathode nozzle 29 supplies a plating solution of 20 to 30 ° C. to the vicinity of the cathode, the plating reaction can be appropriately performed when a plating solution containing a copper sulfate solution as a main component is used.

  A heater 31 is provided in the circulation path between the pump 23 and the anode nozzle 28 as a heating means for heating the plating solution to 25 to 45 ° C. Thereby, since the anode nozzle 28 supplies a plating solution of 25 to 45 ° C. to the vicinity of the anode 13, it is possible to suppress the decomposition of the accelerator.

  Further, a flow rate limiting means 32 for limiting the flow rate of the plating solution is provided in the circulation path between the pump 23 and the anode nozzle 28. As the flow rate restricting means 32, a valve, a nozzle, or the like can be used. As a result, the flow rate of the plating solution supplied from the anode nozzle 28 to the vicinity of the anode 13 is set to 1/3 to 1/4 of the plating solution supplied from the cathode nozzle 29 to the vicinity of the cathode. Specifically, the flow rate of the plating solution is about 12 L / min near the cathode and 4 L / min or less near the anode 13. Thus, decomposition of the additive can be suppressed by reducing the supply rate of the additive to the surface of the anode 13.

  The plating solution supplied from the anode nozzle 28 to the vicinity of the anode 13 contacts the side wall of the plating tank 11 and the anode 13, flows upward, and is supplied to the substrate 14 to be plated. Accordingly, Cu can be supplied from the anode 13 which is a supply source of Cu used for plating to the substrate 14 to be plated.

  As described above, in the plating apparatus according to the second embodiment, two nozzles, the anode nozzle and the cathode nozzle, are provided, the heated plating solution is supplied near the anode, and the plating solution supplied near the anode is supplied. The flow rate is set lower than the flow rate of the plating solution supplied to the vicinity of the cathode. Thereby, decomposition | disassembly of the accelerator which affects an additive, especially embedding property can fully be suppressed, without using a complicated structure.

It is sectional drawing which shows the plating apparatus which concerns on Embodiment 1 of this invention. It is the bottom view (a) and sectional view (b) which show the nozzle used in Embodiment 1. 2 is a cross-sectional view showing an anode used in Embodiment 1. FIG. It is the top view (a) and sectional drawing (b) which show the baffle plate used in Embodiment 1. FIG. It is a figure which shows the temperature dependence of the density | concentration of an additive. It is sectional drawing which shows the plating apparatus which concerns on Embodiment 2 of this invention. 6 is a cross-sectional view showing a nozzle used in Embodiment 2. FIG. It is sectional drawing which shows Cu embedding wiring.

Explanation of symbols

11 Plating tank 13 Anode 14 Substrate to be plated (cathode)
15 Supporting portion 18 Nozzle 20 Current plate (cooling means)
21 Tank 23 Pump 26 Ceramic heater (heating means)
28 Nozzle for anode 29 Nozzle for cathode 30 Cooling means 31 Heater (heating means)
32 Flow rate limiting means

Claims (7)

A plating tank into which an accelerator is added and a plating solution;
An anode made of phosphorous copper,
A support part for supporting a substrate to be plated which becomes a cathode;
Heating means for heating the plating solution in the vicinity of the anode;
And a cooling means for cooling the plating solution flowing from the vicinity of the anode to the vicinity of the cathode.   The plating apparatus according to claim 1, wherein the heating unit is attached to the anode. A plating tank for storing a plating solution to which an accelerator is added;
An anode made of phosphorous copper,
A support part for supporting a substrate to be plated which is a cathode;
An anode nozzle for supplying a plating solution in the vicinity of the anode;
A cathode nozzle for supplying a plating solution to the vicinity of the cathode;
A tank for storing the plating solution;
A pump that pumps the plating solution from the tank and supplies the plating solution to the anode nozzle and the cathode nozzle;
A plating apparatus comprising a heating means provided between the pump and the anode nozzle for heating the plating solution.   The plating apparatus according to any one of claims 1 to 3, wherein the heating means sets the temperature of the plating solution in the vicinity of the anode to 25 to 45 ° C. A plating tank for storing a plating solution to which an accelerator is added;
An anode made of phosphorous copper,
A support part for supporting a substrate to be plated which is a cathode;
An anode nozzle for supplying a plating solution in the vicinity of the anode;
A cathode nozzle for supplying a plating solution in the vicinity of the cathode;
The plating apparatus, wherein a flow rate of the plating solution supplied from the anode nozzle is smaller than a flow rate of the plating solution supplied from the cathode nozzle. A tank for storing the plating solution;
A pump that pumps the plating solution from the tank and supplies the plating solution to the anode nozzle and the cathode nozzle;
The plating apparatus according to claim 5, further comprising a flow rate limiting unit provided between the pump and the anode nozzle and configured to limit a flow rate of the plating solution. 7. The plating according to claim 5, wherein a flow rate of the plating solution supplied from the anode nozzle is 1/3 to 1/4 of a flow rate of the plating solution supplied from the cathode nozzle. apparatus.

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