JP2005139516A - Plating method and plating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce chloride ions taken into a copper plating film. <P>SOLUTION: In the copper plating method using a leveller containing a nitrogen-containing polymer compound, the leveller is beforehand subjected to dechlorination treatment before plating treatment. The dechlorination treatment at this time is performed in such a manner that the weight ratio of chloride ions to 1g of the nitrogen-containing polymer compound is controlled to ≤0.1 g. Further, the plating device provided with: a plating liquid control tank; a dechlorination apparatus for subjecting the leveller to chlorination treatment; a leveller feed part for feeding the leveller subjected to the dechlorination treatment to the plating liquid control tank; and a plating treatment part is used. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a copper plating method, and more particularly to a copper plating method using a dechlorinated leveler, and a leveler and a plating apparatus used therefor.

  Conventionally, aluminum or an aluminum alloy is used as a material for forming a circuit to be wired on a semiconductor substrate. However, as the degree of integration increases, a material having higher conductivity has been demanded. Copper is attracting attention as a material that satisfies this requirement, and copper is formed on a substrate by plating.

  In order to obtain a uniform plating film, various additives such as surfactants, unsaturated organic compounds, and chlorine ions are used in copper plating. Among these additives, chlorine ions are said to be necessary to aid the dissolution of the anode and the action of the brightener (Non-patent Document 1). Some additives are called levelers that flatten plating growth, and nitrogen-containing polymer compounds are generally used as these levelers. Many of these nitrogen-containing polymer compounds are supplied in the form of hydrochloride as tertiary nitrogen or a salt of quaternary nitrogen in order to improve the solubility. Chlorine ions will be included in addition to molecular compounds.

As described above, chlorine ions play an important role in the plating solution. On the other hand, when chlorine ions are taken into a copper-plated plating film, there is a problem that conductivity is lowered. Furthermore, since chlorine ions have corrosivity, there is a problem that corrosion and deterioration of the plated wiring occur.
“Plating textbook” edited by the Electric Plating Society, Nikkan Kogyo Shimbun, p.76

  An object of the present invention is to reduce chlorine ions taken into the plating film.

  As will be described later, the inventors of the present invention are not derived from chlorine ions intentionally added to the plating solution, but from trace amounts of chlorine ions contained in the leveler. As a result, the present invention has been completed based on this finding.

  That is, the present invention is a copper plating method using a leveler containing a nitrogen-containing polymer compound, wherein the leveler is dechlorinated in advance before the plating treatment.

  Moreover, this invention is a leveler for copper plating containing the nitrogen-containing polymer compound whose weight ratio of the chlorine ion with respect to 1 g of nitrogen-containing polymer compound is 0.1 g or less.

  Furthermore, the present invention is a plating solution adjustment tank, a dechlorination device for dechlorinating the leveler, a leveler supply unit for supplying the dechlorinated leveler to the plating solution adjustment vessel, and a plating apparatus comprising a plating treatment unit. .

  The present invention also relates to a plating apparatus for depositing a metal film on a seed layer on a substrate surface by electroplating, wherein a plating solution is applied to a load / unload unit, a substrate transfer device, a cleaning unit, a plating tank, and a plating tank. A plating solution adjusting tank to be supplied, a concentration measuring unit for measuring the concentration of the additive, a dechlorination device for dechlorinating the leveler, and a leveler supplying unit for supplying the dechlorinated leveler to the plating solution, the concentration measuring unit Is a plating apparatus characterized in that the leveler concentration in the plating solution is measured, and based on the measurement result, the leveler supply unit adds the leveler that has been dechlorinated to the plating solution.

  By using the copper plating method, the leveler, or the plating apparatus of the present invention, chlorine ions taken into the copper plating film can be reduced, and corrosion and deterioration of the copper plating wiring can be reduced.

  The leveler usually used for copper plating is used for flattening the plating growth and generally contains a nitrogen-containing polymer compound. The nitrogen-containing polymer compound used here is not particularly limited as long as it is a polymer compound containing a nitrogen molecule in the molecule. For example, polydialkylaminoethyl acrylate, polydiallyldimethylammonium, polyethyleneimine, polyvinylpyridine , Polyvinylamidine, polyallylamine, polyaminesulfonic acid and the like. These nitrogen-containing polymer compounds are in the form of hydrochlorides as tertiary nitrogen or quaternary nitrogen salts in order to improve the solubility in water. Therefore, the leveler contains a nitrogen-containing polymer compound and chloride ions.

  Usually, these levelers are provided as an aqueous solution, which generally contains about 5 to 20 g / L of a nitrogen-containing polymer compound and about 3 to 10 g / L of chlorine ions.

  Then, these levelers are added to the plating solution, and the nitrogen-containing polymer compound contained in the plating solution is usually adjusted to 5 to 20 mg / L. At this time, the chlorine ions contained in the leveler are also dissolved in the plating solution as carry-over, and the concentration is usually several mg / L.

  On the other hand, there is a chlorine ion as another additive used for copper plating. This chloride ion is said to be necessary to aid the dissolution of the anode and the action of the brightener, and is usually added in an amount of 40 to 80 mg / L in the plating solution.

  In this way, the amount of chlorine ions brought into the plating solution as carryover from the leveler is very small compared to the amount of chlorine ions added to the plating solution to aid the dissolution of the anode and the action of the brightener. It has been considered that the chlorine ions brought in as carry-over of the metal does not affect the plating process.

  However, as shown in the examples described later, it has been clarified by the present inventors that chlorine ions brought into the plating solution as carry-over from the leveler are preferentially taken into the plating film. Therefore, chlorine ions taken into the plating film can be reduced by dechlorinating chlorine ions contained in the leveler.

  The leveler dechlorination treatment method used in the present invention is not particularly limited as long as chlorine ions can be reduced, but precipitation or electrolysis is preferred.

As a dechlorination treatment method by precipitation, for example, as shown by the formula (I), it can be performed by adding a substance that forms a hardly soluble salt with chlorine ions such as silver nitrate to the leveler.

As a dechlorination treatment method by electrolysis, for example, as shown in the formula (II), a method of removing chlorine gas at the anode can be mentioned.

  The concentration of chlorine ions contained in the leveler after the dechlorination treatment used in the present invention is preferably 0.1 g or less, more preferably 0.05 g or less, with respect to 1 g of the nitrogen-containing polymer compound. And most preferably 0.01 g or less. When the concentration of chlorine ions exceeds 0.1 g with respect to 1 g of the nitrogen-containing polymer compound, chlorine ions taken into the plating film may increase.

  Moreover, it is preferable that it is 1 g / L or less as a density | concentration of the chlorine ion contained in the leveler after the dechlorination process used for this invention. When this concentration is exceeded, chlorine ions taken into the plating film may increase.

  Hereinafter, the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited to these drawings.

  The plating method, the plating leveler and the plating apparatus of the present invention are mainly used for forming a wiring made of a copper layer by performing electrolytic copper plating on a plating surface of a semiconductor substrate. First, an example of the plating process will be described with reference to FIG.

The semiconductor the substrate W, as shown in FIG. 1 (a), a contact on a conductive layer 1a on the substrate 1 on which semiconductor devices are formed, an insulating film 2 made of SiO ₂ is deposited by lithographic etching technique A hole 3 and a trench 4 for wiring are formed, a barrier layer 5 made of TiN or the like is formed thereon, and a seed layer 7 is formed thereon as a supply layer for electrolytic plating.

  Then, as shown in FIG. 1B, the surface of the semiconductor substrate W is plated with copper so that the contact holes 3 and the grooves 4 of the substrate 1 are filled with copper, and a copper layer is formed on the insulating film 2. 6 is deposited. Thereafter, the copper layer 6 on the insulating film 2 is removed by chemical mechanical polishing (CMP), and the surface of the copper layer 6 filled in the contact hole 3 and the wiring groove 4 and the surface of the insulating film 2 are separated. Make them almost coplanar. As a result, a wiring made of the copper layer 6 is formed as shown in FIG.

FIG. 2 is a diagram showing an example of the plating apparatus 10 of the present invention. As shown in FIG. 2, the plating apparatus 10 of the present invention includes a plating solution adjustment tank 12 that contains a plating solution 14, a concentration measurement unit 16 that is connected to the plating solution adjustment tank 12 via a pipe 15, and a pipe 48. A dechlorination apparatus 60 is provided that includes a carrier supply unit 40 to be connected, a surfactant supply unit 50 connected through a pipe 58, and a leveler supply unit 30 connected through a pipe 38, and further connected to the leveler supply unit 30 through a pipe 67. And a leveler raw material tank 90 connected to the dechlorination device 60 through a pipe 94, and a control unit 18 connected to the concentration measuring unit 16, the leveler supply unit 30, the carrier supply unit 40, and the surfactant supply unit 50, respectively. Further, the plating solution adjusting tank 12 and the pipe 100, the pump 102, the filter 104, and the pipe 108 and the pump 106 are connected to each other. And a can processing unit 70.
Further, as shown in FIG. 2, the leveler supply unit 30 includes a leveler tank 32 that stores a dechlorinated leveler 34, a pump 36 that is connected to the control unit 18, and the carrier supply unit 40 includes a carrier that stores a carrier 44. The tank 42 and the pump 46 connected to the control unit 18 are provided, and the surfactant supply unit 50 includes a surfactant tank 52 containing the surfactant 54 and a pump 56 connected to the control unit 18.

  FIG. 3 is a diagram illustrating an example of the dechlorination apparatus 60 and the leveler raw material tank 90. As shown in FIG. 3, the dechlorination apparatus 60 includes a dechlorination tank 62, a cathode 64, an anode 65, and a stirrer 66. The leveler raw material tank 90 accommodates the leveler raw material 92 and is connected to the dechlorination tank 62 through a pipe 94 and a pump 96.

  FIG. 4 is a diagram illustrating an example of the plating processing unit 70. As shown in FIG. 4, the plating solution 14 is accommodated in the plating tank 76, and the substrate W and the anode 72 mounted on the jig are arranged to face each other in the plating solution 14. A power source 74 is connected between them, and the plating tank 76 is connected to the pipe 100 and the pipe 108.

  FIG. 5 is an overall plan view of an example of the plating processing unit 50. As shown in FIG. 5, the plating processing unit 70 includes four load / unload units 80 that house a plurality of substrates W therein, and four plating application apparatuses 82 that perform the plating process and its ancillary processes. , Two transfer robots 84 and 85 for transferring the substrate W between the load / unload unit 80 and the plating apparatus 82, two bevel / back surface cleaning units 86 and 86, and one film thickness. A measuring device 87 and a temporary substrate mounting table 88 are provided. Here, the plating apparatus 82 is connected to the pipes 100 and 108, respectively, although a part of the illustration is omitted. In FIG. 5, transfer robots 84 and 85 constitute the substrate transfer apparatus of the present invention.

  Note that all the apparatuses relating to the preparation of the plating solution shown in FIG. 2 may be accommodated in the frame of the plating processing unit shown in FIG.

The plating apparatus of the present invention is configured as described above, and the operation thereof will be described below.
The unsealed leveler raw material 92 held in the leveler raw material tank 90 is sent to the dechlorination device 60 by a pump 96 through a pipe 94, and dechlorinated. The leveler raw material 92 charged into the dechlorination tank 62 is uniformly stirred by the stirring bar 66. When a voltage is applied to the anode 65 and the cathode 64, the reaction represented by the formula (II) occurs at the anode 65, and chlorine gas (Cl ₂ ) is generated. Thereby, the dechlorination process of a leveler is performed. The leveler 34 after the dechlorination treatment is sent to the leveler tank 32 of the leveler supply unit 30 by the pump 69 through the pipe 67.

  The plating solution 14 accommodated in the plating solution adjusting tank 12 is sent to the concentration measuring unit 16 to measure the concentration of each additive of the leveler, carrier, and surfactant. Next, the measurement result of each additive is sent to the control unit 18, and when the concentration of each plating solution component is lower than the management concentration set in advance here, the corresponding leveler supply unit 30, carrier supply unit 40, the leveler 34, the carrier 44, and the surfactant 54 that have been dechlorinated from the surfactant supply unit 50 are respectively supplied to the plating solution adjusting tank 12 through the pipes 38, 48, and 58 by the pumps 36, 46, and 56, respectively. And are controlled by the control unit 18 so that each additive is within the control concentration range.

  Then, the plating solution 14 in which the additive concentration is controlled in this way passes through the filter 100 by the pump 102 through the pipe 100 and is sent to the plating processing unit 70, and in the plating tank 76 or the plating apparatus 82. It is used for the plating process of the substrate W. Surfactant, carrier, and leveler are consumed by the plating process, and the plating solution whose concentration is lowered is returned to the plating solution adjusting tank 12 by the pump 106 through the pipe 108 again.

  Next, the operation of the plating processing unit 70 will be described. First, as an example of the plating processing unit 70, in FIG. 4, the plating solution 14 in which the additive concentration is controlled is supplied to the plating tank 76 through the pipe 100 through the filter 104 by the pump 102. Then, when a voltage is applied between the anode 72 and the substrate W by the power source 74, copper plating is formed on the surface of the substrate W. Then, the plating solution after the plating treatment is returned again to the plating solution preparation tank 12 by the pump 106 through the pipe 108.

  As another example of the plating processing unit 70, in FIG. 5, the transfer robot 84 takes out the substrate W before plating processing from the wafer cassette mounted on any of the load / unload units 80, and the substrate W is formed into a film thickness. By conveying to the measuring device 87, the plating film thickness of the substrate W before plating is measured. Next, the transfer robot 84 takes out the substrate W in the film thickness measuring device 87 and places it on the temporary substrate table 88. Next, with the other transfer robot 85 hand taking out the substrate W on the temporary substrate mounting table 88 and with the surface to be plated facing upward, it is carried into the inside through the substrate carry-in / out port provided in one of the plating apparatuses 82. To do. Then, the plating solution 14 whose additive concentration is controlled is supplied from the plating solution adjustment tank 12 through the pipe 100 to the plating apparatus 88 through the filter 104 by the pump 102, and the plating process is performed. The plating solution after the plating treatment is returned again to the plating solution adjusting tank 12 by the pump 106 through the pipe 108.

  After the plating process is completed, the substrate W is taken out from the plating apparatus 85 by the transfer robot 85. The taken-out substrate W is transported to one of the bevel / back surface cleaning units 86, cleaned and dried, and then placed on the temporary substrate mounting table 88 by the transport robot 85, and the film thickness measuring device 87 is transported by the transport robot 84. After the film thickness of the substrate W after plating is measured, the film is stored in a wafer cassette attached to any load / unload unit 80 by the transfer robot 84. As a result, the plating process for one substrate W is completed.

  In order to confirm that the chlorine ions taken into the plating film are derived from the leveler, the following test was performed.

First, 1 g of a plating solution containing 200 g of CuSO ₄ .5H ₂ O, 10 g of H ₂ SO ₄ , 60 mg of chloride ions, 200 mg of polyethylene glycol (molecular weight of about 3000) and 5 mg of bis (3-sulfopropyl) disulfide was prepared. .

To this, polyvinyl pyridine quaternary ammonium hydrochloride before dechlorination treatment was used as a leveler, and added to the plating solution so that polyvinyl pyridine was 10 mg / L in the plating solution. The leveler before dechlorination treatment contained 16 g / L of polyvinyl pyridine and 4 g / L of chlorine ions. Copper plating was performed on the silicon wafer using this plating solution.
Similarly, copper plating was performed on the silicon wafer using a plating solution to which no leveler was added.

  Next, chlorine ions taken into the copper plating film were measured by SIMS (secondary ion mass spectrometer) on the silicon wafer subjected to copper plating. As a result, it was confirmed that the amount of chlorine ions contained in the copper plating film when a leveler containing chlorine ions was used was about 10 times higher than that when no leveler was used.

  Therefore, it has been clarified that chlorine ions brought into the plating solution as carry-over from the leveler are preferentially taken into the plating film.

  Next, the leveler used in Example 1 was dechlorinated to produce a leveler having a chlorine ion concentration reduced to 1 g / L.

  Using this leveler after dechlorination, copper plating was applied to the silicon wafer using the same plating solution as in Example 1.

  It can be confirmed that the amount of chlorine ions in the copper plating film is reduced by measuring the chlorine ions taken into the copper plating film by SIMS in the same manner as in Example 1.

FIG. 1 is a cross-sectional view showing an example of a plating process. FIG. 2 is a diagram showing an example of the plating apparatus of the present invention. FIG. 3 is a diagram showing an example of a dechlorination apparatus and a leveler raw material tank used in the present invention. FIG. 4 is a diagram showing an example of a plating processing unit used in the present invention. FIG. 5 is a diagram showing an example of a plating processing unit used in the present invention.

Explanation of symbols

W substrate 1 substrate 1a conductive layer 2 insulating film 3 contact hole 4 groove 5 barrier layer 6 copper layer 7 seed layer 10 plating apparatus 12 plating solution adjustment tank 14 plating solution 15 piping 16 concentration measuring unit 18 control unit 30 leveler supply unit 32 leveler Tank 34 Dechlorinated levelers 36, 46, 56 Pumps 38, 48, 58 Piping 40 Carrier supply section 42 Carrier tank 44 Carrier 50 Surfactant supply section 52 Surfactant tank 54 Surfactant 60 Dechlorination device 62 Dechlorination Tank 64 Cathode 65 Anode 66 Stirrer 67 Pipe 69 Pump 70 Plating treatment section 72 Anode 74 Power supply 76 Plating tank 80 Load / unload section 82 Plating equipment 84, 85 Transport robot 86 Cleaning unit 87 Film thickness measuring apparatus 88 Temporary substrate mounting table 90 Leveler material tank 92 Leveler material 94 Piping 96 Pump 100 , 108 Piping 102, 106 Pump 104 Filter

Claims (7)

A copper plating method using a leveler containing a nitrogen-containing polymer compound, wherein the leveler is dechlorinated in advance before the plating treatment. 2. The copper plating method according to claim 1, wherein a weight ratio of chlorine ions to 1 g of the nitrogen-containing polymer compound is set to 0.1 g or less by the dechlorination treatment. The copper plating method according to claim 1 or 2, wherein a chlorine ion concentration contained in the leveler is set to 1 g / L or less by the dechlorination treatment. The copper plating method according to claim 1, wherein the dechlorination treatment is performed by precipitation or electrolysis. Leveler for copper plating containing a nitrogen-containing polymer compound, wherein the weight ratio of chlorine ions to 1 g of the nitrogen-containing polymer compound is 0.1 g or less. A plating apparatus comprising a plating solution adjustment tank, a dechlorination device for dechlorinating the leveler, a leveler supply unit for supplying the dechlorinated leveler to the plating solution adjustment tank, and a plating treatment unit. A plating apparatus for depositing a metal film on a seed layer on a substrate surface by electroplating, and a plating solution adjusting tank for supplying a plating solution to a load / unload unit, a substrate transfer device, a cleaning unit, a plating tank, and a plating tank A concentration measuring unit that measures the concentration of the additive, a dechlorination device that dechlorinates the leveler, and a leveler supply unit that supplies the dechlorinated leveler to the plating solution, the concentration measuring unit being a leveler in the plating solution A plating apparatus characterized by measuring a concentration and adding a leveler from which the leveler supply section has been dechlorinated based on the measured result to a plating solution.

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