MXPA00003455A - Copper metallization of silicon wafers using insoluble anodes - Google Patents
Copper metallization of silicon wafers using insoluble anodesInfo
- Publication number
- MXPA00003455A MXPA00003455A MXPA/A/2000/003455A MXPA00003455A MXPA00003455A MX PA00003455 A MXPA00003455 A MX PA00003455A MX PA00003455 A MXPA00003455 A MX PA00003455A MX PA00003455 A MXPA00003455 A MX PA00003455A
- Authority
- MX
- Mexico
- Prior art keywords
- copper
- electrolyte
- tank
- cathode
- plating
- Prior art date
Links
- 239000010949 copper Substances 0.000 title claims abstract description 178
- RYGMFSIKBFXOCR-UHFFFAOYSA-N copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims abstract description 176
- 229910052802 copper Inorganic materials 0.000 title claims abstract description 176
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 14
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 14
- 239000010703 silicon Substances 0.000 title claims abstract description 14
- 235000012431 wafers Nutrition 0.000 title abstract 2
- 238000001465 metallisation Methods 0.000 title description 4
- 239000003792 electrolyte Substances 0.000 claims abstract description 136
- 238000007747 plating Methods 0.000 claims abstract description 72
- 238000009713 electroplating Methods 0.000 claims abstract description 54
- 238000007792 addition Methods 0.000 claims abstract description 10
- 239000000758 substrate Substances 0.000 claims description 37
- 239000000654 additive Substances 0.000 claims description 36
- 230000000996 additive Effects 0.000 claims description 31
- 238000000034 method Methods 0.000 claims description 25
- 239000004065 semiconductor Substances 0.000 claims description 10
- -1 copper silicon Chemical compound 0.000 claims description 7
- 238000003756 stirring Methods 0.000 claims description 7
- ARUVKPQLZAKDPS-UHFFFAOYSA-L Copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 claims description 6
- 229910000365 copper sulfate Inorganic materials 0.000 claims description 5
- 230000001186 cumulative Effects 0.000 claims description 3
- 239000011120 plywood Substances 0.000 claims description 2
- 239000002000 Electrolyte additive Substances 0.000 claims 2
- 230000003134 recirculating Effects 0.000 abstract 1
- 229910052751 metal Inorganic materials 0.000 description 12
- 239000002184 metal Substances 0.000 description 12
- 238000004519 manufacturing process Methods 0.000 description 9
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 8
- 239000002253 acid Substances 0.000 description 6
- 239000012535 impurity Substances 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- QAOWNCQODCNURD-UHFFFAOYSA-L sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminum Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 229910052697 platinum Inorganic materials 0.000 description 4
- 238000005201 scrubbing Methods 0.000 description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 4
- 239000010936 titanium Substances 0.000 description 4
- 229910052719 titanium Inorganic materials 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 3
- 229910001431 copper ion Inorganic materials 0.000 description 3
- JZCCFEFSEZPSOG-UHFFFAOYSA-L copper(II) sulfate pentahydrate Chemical compound O.O.O.O.O.[Cu+2].[O-]S([O-])(=O)=O JZCCFEFSEZPSOG-UHFFFAOYSA-L 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- YJZATOSJMRIRIW-UHFFFAOYSA-N [Ir]=O Chemical compound [Ir]=O YJZATOSJMRIRIW-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005868 electrolysis reaction Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 229910000457 iridium oxide Inorganic materials 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000006011 modification reaction Methods 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 229910001369 Brass Inorganic materials 0.000 description 1
- DOBRDRYODQBAMW-UHFFFAOYSA-N Copper(I) cyanide Chemical compound [Cu+].N#[C-] DOBRDRYODQBAMW-UHFFFAOYSA-N 0.000 description 1
- 206010053759 Growth retardation Diseases 0.000 description 1
- 210000002381 Plasma Anatomy 0.000 description 1
- 229920001021 Polysulfide Chemical class 0.000 description 1
- 239000005092 Ruthenium Substances 0.000 description 1
- RRJHFUHAKCSNRY-UHFFFAOYSA-L [Cu+2].[O-]P([O-])=O Chemical compound [Cu+2].[O-]P([O-])=O RRJHFUHAKCSNRY-UHFFFAOYSA-L 0.000 description 1
- SXFNQFWXCGYOLY-UHFFFAOYSA-J [Cu+4].[O-]P([O-])(=O)OP([O-])([O-])=O Chemical compound [Cu+4].[O-]P([O-])(=O)OP([O-])([O-])=O SXFNQFWXCGYOLY-UHFFFAOYSA-J 0.000 description 1
- ROZSPJBPUVWBHW-UHFFFAOYSA-N [Ru]=O Chemical compound [Ru]=O ROZSPJBPUVWBHW-UHFFFAOYSA-N 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 229910052803 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- HMUNZEYTSRPVBE-UHFFFAOYSA-N copper;ditetrafluoroborate Chemical compound [Cu+2].F[B-](F)(F)F.F[B-](F)(F)F HMUNZEYTSRPVBE-UHFFFAOYSA-N 0.000 description 1
- JPVYNHNXODAKFH-UHFFFAOYSA-N cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 description 1
- 230000003247 decreasing Effects 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000003999 initiator Substances 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 229910052752 metalloid Inorganic materials 0.000 description 1
- 150000002738 metalloids Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- XGZVLEAZGCUUPH-UHFFFAOYSA-N methylamino(methylimino)methanesulfonic acid Chemical compound CNC(=NC)S(O)(=O)=O XGZVLEAZGCUUPH-UHFFFAOYSA-N 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000006259 organic additive Substances 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 150000004686 pentahydrates Chemical class 0.000 description 1
- 230000000737 periodic Effects 0.000 description 1
- 230000021715 photosynthesis, light harvesting Effects 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229920000768 polyamine Polymers 0.000 description 1
- 229920000570 polyether Polymers 0.000 description 1
- 239000005077 polysulfide Chemical class 0.000 description 1
- 150000008117 polysulfides Chemical class 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 229910001925 ruthenium oxide Inorganic materials 0.000 description 1
- BUGBHKTXTAQXES-UHFFFAOYSA-N selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 1
- 229910052711 selenium Inorganic materials 0.000 description 1
- 239000011669 selenium Substances 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 235000011149 sulphuric acid Nutrition 0.000 description 1
- 229910052714 tellurium Inorganic materials 0.000 description 1
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Abstract
A plating system (10) and method are provided for electroplating silicon wafers with copper using an insoluble anode (13) wherein the electrolyte is agitated or preferably circulated through an electroplating tank (11) of the system and a portion of the electrolyte is removed from the system when a predetermined operating parameter is met. A copper-containing solution having a copper concentration greater than the copper concentration of the removed portion is added to the copper plating system (10) simultaneously or after electrolyte removal, in a substantially equal amount to the electrolyte removed from the system and balances the amount of copper plated and removed in the removal stream. In a preferred method and system, an electrolyte holding tank (19) is provided which serves as a reservoir for circulating electrolyte. The addition of the copper-containing solution and removal of working electrolyte is also preferably made from the holding tank (19). The preferred apparatus is preferably cylindrical and is specially configured so that recirculating electrolyte enters near the anode (13) and exits near the cathode (12) with the outlet of the apparatus having a substantially continuous opening around the periphery of the electroplating tank (11) so that electrolyte exiting the tank has a substantially uniform flow across the surface of the cathode (12). The anode (13) is preferably circular and has a central through opening (13a) through which the entering electrolyte passes.
Description
METALIZATION WITH COPPER SILICON DISCS USING INSOLUBLE ANODES
DESCRIPTION Field of the Invention 5 • This invention relates to a method and a system for coating substrates with copper and, in particular, refers to the electrolytic copper metallization of silicon disks using insoluble anodes. Background of the Invention 10 The demand for the manufacture of devices for
• Semiconductor integrated circuits (ICs), such as computer chips with high-speed circuits, high-density packaging and low energy dissipation, require a smaller scale of size for
characteristics related to structures that have an excessively large scale of integration (EEEG) or structures that have a very large scale of integration (EEMG). The tendency to decrease chip sizes
• and increasing the density of the circuit requires the
miniaturization of the interconnection characteristics, which severely punishes the entire performance of the structure, due to the increase in the interconnection resistance and the problems of operation, such as in the manufacture of interconnections and in the electroemigration. In the present, such structures use aluminum and aluminum alloys as the metallization of silicon discs with silicon dioxide (SiO2) which is the dielectric material. In general, openings are formed in the dielectric layer of Si02 with configurations of channels and channels that are metallized forming the interconnections, increasing miniaturization, by reducing the openings to sub-strata (for example, 0.5 microns and lower values). However, to achieve additional miniaturization, it is proposed to use copper instead of aluminum, as the metal to form the connection lines on the chip. Copper has a lower resistivity than aluminum and the thickness of the copper line for the same resistance can be thinner than that of the aluminum line. Therefore, copper-based interconnections represent the future trend for the manufacture of such devices. Copper can be deposited on substrates by plating (such as an electrolytic plating and plating without electrodeposition), electronic deposition, vapor plasma deposition (DEV) and chemical vapor deposition (DPQV). It is generally recognized that a plating-based deposition is the best method to apply copper to the device, since it can provide deposition at high speeds and with low tool costs. However, the plating methods must meet the stringent requirements of the semiconductor industry. For example, copper deposits should be uniform and capable of filling the extremely small channels and channels of the device. The veneering process must also be able to be controlled in such a way that the problems of plating are avoided or avoided and must also be compatible with the operations of the depuration rooms. In the electronics industry it is recognized that the deposition of copper from acid copper baths is the outstanding candidate for copper plating integrated circuit devices. In general, electroplating with copper comprises the deposition of a copper layer on a surface by means of electrolysis, using a consumable copper electrode or an insoluble anode. In the consumable electrolytic plating process, the copper electrode is consumed during the plating operation and must be periodically replaced during the plating operation. When the plating process uses insoluble anodes, these anodes are not consumed in the plating process and do not have to be replaced. The following description will be directed to copper electrolytic plating using insoluble anodes. Without considering the method used for the deposition of copper on the substrate, surface impurities can be deposited together with the copper. In the manufacture of integrated circuits, it is important that the particles of the impurities are not present in the electrolyte, but such impurities can result from sludge formed during the operation of plating, impure chemicals and the like. As in all the processes used to manufacture the integrated circuit (Cl) devices, it is necessary that such impurities are minimized and most operations are carried out in a debug room. A purification room is basically a room in which the different steps of the process are carried out and dust particles and other impurities particles are kept below certain levels through the use of filters and other purification or cleaning devices. It is important that any plating process for the manufacture of integrated circuit devices can be adapted to be used in a scrubbing room and that the process itself minimizes the problems of the impurities inherent in the plating process. Viewing the problems and deficiencies of the prior art, accordingly, it is an object of the present invention to provide an improved method and apparatus (system) for electroplating a substrate. It is a further object of the present invention to provide an improved electrolytic method and apparatus for copper plating a silicon disk during the manufacture of integrated circuits using an insoluble anode. It is another object of the present invention to provide an electrolytic method and apparatus for copper plating a substrate, including the substrates of a silicon disk employing an insoluble anode, the plating can be carried out in a scrubbing room. It is a further object of the invention to provide a plating process with electrolytic copper having an electrolyte in a substantially stable condition, wherein the plating properties of the deposit remain constant. Another object of the invention is to provide semiconductors and other electroplating devices with copper. Other objects and advantages of the invention, in part, will be readily apparent from the following description. Disclosure of the Invention Applicants have discovered an electrolytic method for copper plating a substrate, preferably a silicon disk semiconductor substrate comprising: providing a plating system comprising a copper plating apparatus comprising a tank having preferably an inlet and an outlet and contains a copper electrolyte and a substrate to be plated as a cathode and a separate insoluble anode; stir the copper electrolyte in the tank,
Preference is given to circulating the electrolyte at the inlet of the tank and simultasly withdrawing the copper electrolyte from the outlet of the tank, while a current is applied and the cathode is electroplated; measuring at least one of the parameters of the operation of the plating system; • removing a part of the electrolyte from the system when a predetermined operating parameter is reached; adding to the system, either simultasly with removal of the electrolyte or after removal of the electrolyte, a solution containing copper having a copper concentration greater than the copper concentration of the removed electrolyte and in an amount sufficient to increase the concentration of electrolyte copper in the system to a
• predetermined value and to maintain the volume of the electrolyte in the system in a substantially constant volume. In another aspect of the invention, there is provided a method for electroplating a substrate, preferably a semiconductor substrate of a silicon disk, comprising: providing a plating system comprising: a copper plating tank and a copper plating tank; electrolyte container tank, the copper plating tank is preferably cylindrical and has an entry preferably
• 5 . at the lower end of the tank and an outlet at the upper end of the tank and containing a copper electrolyte and a substrate as a cathode and a separate insoluble anode, both the cathode and the anode are preferably horizontal, the inlet and outlet of preference is placed 10 so that the electrolyte current enters the tank
• plated near the anode and near the cathode; agitate the electrolyte, preferably by circulating the copper electrolyte to the inlet of the apparatus from the holding tank and simultasly removing the copper electrolyte from the outlet of the apparatus and directing the copper electrolyte from the outlet to the holding tank, while that a current is applied and the cathode is electroplated; • measure at least one c of the parameters of the operation of the plating system; removing a part of the electrolyte from the system when a predetermined operating parameter is reached; add to the system, either simultasly with the removal of the electrolyte or after removal of the electrolyte,
A solution containing copper having a copper concentration greater than the copper concentration of the removed electrolyte and in an amount sufficient to increase the copper concentration of the electrolyte in the system to a predetermined value and to maintain the volume of the electrolyte. in the system in a substantially constant volume. In another aspect of the invention, an apparatus for electrolytic copper plating a substrate, preferably a silicon disk, comprising: an electroplating tank containing a copper electrolyte, a substrate as a cathode and a separate insoluble anode, the tank preferably has an inlet element and an outlet element; stir the copper electrolyte in the tank,
Preference is given to circulating the copper electrolyte through the electroplating tank from the inlet to the outlet, while a current is applied and the cathode is electroplated; a measuring element for measuring at least one of the operating parameters of the plating process; a removal element for removing the electrolyte from the electroplating tank when a predetermined operating parameter is reached; and an addition element for adding to the electroplating tank a copper containing solution having a copper concentration greater than the copper concentration of the removed electrolyte in an amount sufficient to increase the copper concentration of the electrolyte in the system to a value predetermined and to maintain the volume of the electrolyte in the system in a substantially constant volume. In a preferred embodiment, the apparatus further comprises a filtering element for filtering the electrolyte and / or a cooling / heating element for adjusting the electrolyte temperature. It is preferred to filter the electrolyte when it enters the electroplating tank. In another aspect of the invention, the apparatus further comprises an electrolyte holding tank from which the electrolyte is pumped at the entrance of the electroplating tank and into which the electrolyte is pumped at the outlet of the electroplating tank. The addition element adds the solution containing copper, preferably adding the solution to the container tank. The electrolyte removed from the system is also preferably removed from the container tank. In another aspect of the invention, the additive solution containing copper is packaged in a container containing a predetermined amount of the solution to be added to the system and added by means of elements suitable for the operations of the depuration room, for example, Inject the solution into the container tank from the container, and the container either disposed of or available for refilling and reuse. Also, the electrolyte that is removed from the system is preferably removed in a waste container under conditions suitable for the operations of the scrubbing room and said container can be removed from the system and the contents can be treated outside the scrubbing room. Brief Description of the Drawings • Various aspects of the present invention can be understood with reference to the accompanying drawings in which: Figure 1 is a schematic illustration of a
The copper electroplating apparatus of the invention employs a container tank to recycle the copper electrolyte. Figure 2 is a schematic illustration of another
• copper electroplating apparatus of the invention. MODE (S) FOR CARRYING OUT THE INVENTION In describing the preferred embodiment of the present invention, reference will be made to Figures 1-2 of the drawings in which similar numbers refer to similar features of the invention. The
features of the invention are not necessarily shown in scale in the drawings. With reference to Figure 1, a plating system of the invention is shown, generally as 10 and a substrate 12 is used for electroplating with copper. The plating system 10 and the method are described with reference to the plating of a disc. of silicon employing an insoluble anode, but those skilled in the art will appreciate that other substrates can be veneered. The preferred veneering system 10 comprises an electroplating tank 11 which contains the copper electrolyte 27 and which is made of a suitable material, such as a plastic or other inert material within the electrolytic plating solution. The tank is preferably cylindrical for the plating of the disk. A cathode 12 is arranged horizontally in the upper part of the tank 11 and can be any type of substrate, such as a silicon disk having openings such as channels or tracks. The disk substrate 12a, typically, is coated with a copper or other metal initiator layer to initiate plating thereon. The copper starter layer can be applied by CVP, PVD and the like. Likewise, the anode 13 is preferably circular for plating the disc and is arranged horizontally in the lower part of the tank 11 that forms a space between the anode 13 and the cathode 12. The anode 13 is an insoluble anode that is not consumed in the process. Suitable insoluble anodes include platinum and platinum metals, including platinum titanium and platinum niobium and metal oxides, for example, iridium oxide, ruthenium oxide, etc. coated on the substrate such as titanium. The substrate of the cathode 12 and the anode 13 are electrically connected, via the wires 14 and 15 respectively, with a rectifier 16 (the power supply). The substrate of the cathode 12 with the direct current has a negative charge, so that the copper ions in the solution are reduced in the cathode substrate by forming the copper metal plated on the cathode surface 12a. At the anode 13 an oxygen-forming oxidation reaction is carried out which migrates from the surface of the anode in the form of bubbles which are raised to the tank 11. The cathode 12 and the anode 13 are shown arranged horizontally, but may also be vertically disposed in the tank 11. An electrolyte holding tank 19 contains the copper electrolyte 27 which is recycled from the holding tank 19 through the pipe 17a, the filter 26 and the pipe 17b to the entrance lla of the electroplating tank 11 The electrolyte 27 when it enters the tank moves through an opening 13a in the anode 13 and moves upwards, as shown by the arrows A, in the direction of the outlets 11b and 11b 'of the electroplating tank 11. anode 13 is placed on the plate 31. Arrows B show the electrolyte that is removed from the container tank 11 through the outlets 11b and 11b 'which are close to the edge of the surface 12a of the cathode or 12 and it is more preferred that the outlet be a continuous opening around the periphery of the electroplating tank, so that the electrolyte flow interferes on the cathode surface which is uniform across the cathode surface and the electrolyte is overflow the opening and be directed towards the container tank 19 to be recycled. The electrolyte flows through the opening 13a and flows up through the tank 11 and interferes with the cathode 12 when it leaves the tank 11. A flange or plate 30 holds the cathode 12 in position. As the picture shows, the electrolyte is in contact only with the upper side of the anode 13 and only with the lower side 12a of the cathode 12. The outlet electrolyte is recycled in the container tank 19 and the electroplating tank 11. This forms a composition in the system substantially uniform electrolytic and contributes to all the effectiveness of substrate plating. The electroplating bath with copper can vary widely depending on the substrate to be plated and the type of copper deposit desired. An acid bath is preferred and a copper plating bath is exemplary due to the demonstrated effectiveness of the copper ion at a concentration of approximately 15 to 19 g / 1 and the demonstrated effectiveness of copper sulfate as a pentahydrate at a concentration of 59 to 75 g / 1. Sulfuric acid is present in an amount of approximately 150 to 225 g / 1. A chloride ion can also be used in the bath at a level up to 90 mg / 1. The bath also preferably contains an additive system for the properties of polish, ductility and other properties of the copper-plating process. During the operation of the electroplating system 10, the copper metal is plated on the surface 12a of the cathode substrate 12 when the rectifier 16 is activated. Pulsed current, direct current, reverse periodic current or other suitable current can be used. The electroplating process causes a reduction in the copper concentration of the copper electrolyte 27. The temperature of the electrolyte can be maintained by using a heater / cooler 22, by which, the electrolyte 27 is removed from the container tank 19 and flowed to the through the pipe 23 and the heater / cooler 22 and is recycled in the holding tank 19 through the pipe 24. It is an important feature of the invention that is to control the plating system and the method of the invention, by removing a part of the electrolyte of the system, when a predetermined operating parameter (condition) is reached and a new electrolyte is added to the system substantially in the same amount, either simultaneously with the removal of the electrolyte or after removal of the electrolyte. The new electrolyte is preferably a simple liquid containing all the materials necessary to maintain the electroplating bath and the electroplating system. The addition / removal system of the invention maintains the constant plating system in a stable condition that has improved plating effects, such as in the constant plating properties. It has been found that by employing the system and method of the invention that the plating bath achieves a stable condition, when the bath components are substantially non-cumulative, for example, achieving a value for a stable condition, such as the sulfate concentration. The electrolyte is added as a solution containing copper that has a copper concentration greater than the copper concentration of the electrolyte removed from the system and increases the copper concentration in the electrolyte in the system to a predetermined value, typically at the value of the initial copper and / or the value of the copper that is going to be maintained. This removal and addition is achieved by removing electrolyte 27 which is essentially homogeneous from tank 19 through pipe 29 to tank or tank 21. A solution containing copper is added to tank container 19 through pipe 18 from the container or tank 20. In an operation mode, the electrolyte is removed and the copper-containing solution is added based on the operation parameter related to the amount of copper plated in the system, by virtue of the last addition procedure /removal. This can be determined in a large number of roads, such as amp-hours, weight of the
copper, etc. In any case, when a certain amount of
• copper is veneered, it is preferred that a certain amount of electrolyte be removed from the system and an equal amount of the solution containing copper be added to the system. It is preferred that the amount of copper added in the solution
that contains copper is equal to the amount plated on the substrate plus the amount removed in the removed stream. This will keep the copper concentration within a range that can be controlled within certain limits,
• depending on the desired veneering characteristics. HE
It is preferred that the copper concentration in the electrolyte be maintained at about 3 g / 1, preferably at 2 g / 1 and more preferably at 1 g / 1 or at a lower concentration of copper for the plating process of a disk. The copper used to make the electrolyte and the
The copper-containing solution is preferably copper sulfate. It has been found that when the system and method of the invention is used with copper sulfate and an additive containing a sulfate in which the sulphate concentration of the bath is maintained at an effective level of operation throughout the entire operation. of plating and the concentration of sulphate need not be measured or controlled separately. The copper-containing solution also contains an additive system that is the same additive system used in the electrolyte. The amount of additive that is used during the
plywood operation can be determined empirically and
• the value decreases during the plating time. It has also been found that using the system and method of the invention, when the amount of additive added in the copper-containing solution is substantially equal to the amount of the
The additive that is calculated is to be used during the plating process plus the amount withdrawn from the system in the removal stream, the level of additive is maintained at the desired concentration or range of electrolyte without the
• need for a separate measurement or other control process.
Therefore, it is not necessary to measure the amount of the additive in the electrolyte or perform other analytical measurements on the additive when using the method and plating system of the invention. With reference now to Figure 2, which shows
In another plating system 10 of the invention, the plating system 10 is similar to the plating system of Figure 1, except that a container tank 19 is not used. So the electroplating tank 11 has a cathode therein. 12 and an anode 13 arranged horizontally, separated by a space. The electrolyte 27 in the tank is circulated through the tank and removed through the outlet pipes 18a and 18b. The outlet from the tank is recycled to the inlet of the tank through the pipe 17a, the filter 26 and the pipe 17b inside the tank 11 to the inlet lia. The arrows A show the electrolyte flow 27 inside the tank and the arrows B show the flow of the electrolyte towards the outlets 11b and 11b 'passing through the cathode 12. The anode 13 has a central opening 13a. When a predetermined operating parameter is reached, the electrolyte 27 is removed from the apparatus through the pipe 29 inside the tank or vessel 21 and the copper-containing solution in the tank 20 is fed to the outlet pipe 18a through the pipe 28. The heater or cooler 22 used in the pipe 18a is shown. Preferred insoluble anodes include platinum and platinum metal surfaces and iridium oxides on a substrate such as titanium. Generally, these anodes are made by coating these compounds on a conducting substrate, such as a titanium substrate.
Other anodes may also be employed in practicing the invention, and generally comprise a Group VIII metal. Group VIII metals include cobalt, nickel, ruthenium, rhodium, palladium, iridium and platinum. • 5 The invention can be practiced using a wide variety of copper baths. Electrolytic baths include acid baths and alkaline baths. A variety of electroplating baths are described in the book entitled Modern Electroplating, edited by F.A. Lowenheim, John Reily
& Sons, Inc., 1974, pages 183-203. Exemplary, the baths include copper fluoborate, copper pyrophosphate, copper cyanide, copper phosphonate and other copper metal chelates, such as methane sulphonic acid and the copper electroplating bath comprising a copper sulfate
in an acid solution. The concentration of copper and acid can vary within a range of limits. For copper or copper ions, the compositions generally vary up to 25 g / 1 or a higher value, preferably from 15 to 20 g / 1. The
• acid solution is typically sulfuric acid in an amount
approximately 300 g / 1 or more preferably between 150 to 200 g / 1. Chloride ions can be used in the bath at approximate levels of 90 mg / 1. Typically a large variety of additives are used in the bath to provide the desired surface finish
for copper-plated metal. Usually more than one additive is used with each additive forming the desired function. Additives generally used to improve the metal's veneered appearance (brightness), ductility, structure and physical properties, such as conductivity
• 5 electric. Particular additives (usually organic additives) are used for granular refining, dendritic growth suppression and improving coverage and switching energy. The typical additives used in the electroplating process are discussed in a number of references with
inclusion of Modern Electroplating, mentioned above. A particularly desirable additive system uses a mixture of aromatic or aliphatic quaternary amines, polysulfide compounds, polyamines and polyethers. Other additives include metalloids, such as selenium, tellurium and compounds of
sulfur. The electrolysis conditions such as the concentration of electric current, applied to the voltage, the density of the electric current, and the temperature of the
• electrolyte can be essentially the same as those of
conventional methods for plating with electrolytic copper. For example, the temperature of the bath is approximately the room temperature, approximately 20 to 27 ° C, but the temperature of the bath may be elevated temperatures of approximately 40 ° C or a
higher temperature. The density of the current typically has an approximate value of 100 amps per square foot (ASF), typically has an approximate value between 15 to 40 ASF. It is preferred to use a ratio between the anode and the cathode approximately 2: 1, but this can also vary widely
• 5 to an approximate ratio of 1: 1 to 4: 1. The method of the invention also uses mixing in the electroplating tank, which can be provided by stirring or preferably by circulating the flow of recycled electrolyte through the tank. In the device
Preferred of the invention as shown in the Figures, the
• flow through the electroplating tank provides a residence time of the electrolyte in the tank of less than about 1 minute, typically less than 30 seconds, for example, between 10 to 20 seconds. The solution containing copper that is added to the system to provide the copper plated on the substrate and removed from the system in the removal stream can be any suitable concentration. It is preferred that
• the solution is a copper sulphate solution near the
The saturation level of copper sulphate pentahydrate, for example, approximately between 275 to 325 g / 1, which is approximately between 80 to 80 g / 1 of copper. As discussed above, the amount to be used of the copper-containing solution also contains an amount of the additive
used during the plating process plus the amount removed from the removal stream. It is a preferred important aspect of the invention, regardless of the concentration of copper in the copper-containing solution, that a substantially equal amount of the circulating electrolyte is
• 5 removed from the system when added to the system and it is more preferred that the aggregate amount be minimized by use, for example, a solution containing concentrated copper. Using this addition / removal procedure keeps the electrolyte in a proper condition for
electroplate the substrate and provide a bath that has
• Long life and improves the operation and the effects of veneering. Various embodiments of the present invention will now be illustrated with reference to the following examples
specific. However, it is understood that such examples are presented solely for purposes of illustration and the present invention is in no sense considered to be limited thereto. Example 1 An electroplating bath was prepared with copper with approximately 1 gallon containing 67 g / 1 of copper sulphate pentahydrate (17 g / 1 Cu + 2), 190 g / 1 of H2SO4 and 8 ml / 1 of the additive system. 5.08 cm polished brass cathode substrate was suspended vertically in the bath
(2 inches) x 7.62 cm (3 inches). A pair of titanium-plated titanium anodes, each with a size of 5.08 cm (2 inches) x 15.24 cm (6 inches) (when immersed in the bath), were also suspended vertically in the bath, on each side of the cathode with a Approximate space of 7.62 cm (3 inches) between the cathode and each anode. The bath was agitated using a magnetic stirrer. The temperature of the bath was maintained approximately between 21 to 27 ° C, an electrical current of CD A was used at 25 amps per square foot (ASF). A solution containing copper containing 75 g / 1 Cu + 2 (added as copper sulfate pentahydrate) and 235 ml / 1 of the same additive system was prepared. After 6 grams of copper was plated from the 1 gallon bath, 100 ml of the operating electrolyte was removed and 100 ml of the copper-containing solution was added. This procedure was followed for 1 shift of metal production (the time required to coat the initial copper in the electrolyte which is approximately 6 g of copper). The copper bath was maintained in a material balance as follows. For every 6 g. of copper plating, 100 ml of the electrolyte was removed by stirring a 1.5 g. Additional copper bath operating for a total of 7.5 g. of copper removed from the system. 100 ml of the copper-containing solution adds approximately 7.5 g to the bath. coppermade. Also, for every 6 g. of plated copper, approximately 22.5 ml of the additive was consumed and approximately 0.8 ml were removed in the electrolyte removal part. 100 ml of the copper-containing solution contains approximately 23.5 ml of the additive. The consumption of the additive was determined empirically. Using the above procedure, essentially achieved 100% of the efficiency of the plating (based on the increase in the weight of the copper, the density of the plating current and the time of plating). The copper concentration was maintained at approximately 15 to 17 g / 1 during a 1-shift veneer cycle of metal production. The total sulfate concentration decreased approximately 5%. Clear, consistent and constant copper electroplating results were obtained. Example 2 An electroplating apparatus with copper (basically as shown in Figure 1) was used to electroplate copper onto a silicon disk with a diameter of 20.32 cm (8 inches) having channels and tracks. The insoluble anode has approximately a diameter of 20.32 cm (8 inches) which has a central opening for the flow of the electrolyte therethrough and is made of platinum titanium. The bath temperature was maintained at about 21 to 27 ° C and the electrolyte was circulated through the apparatus at about 15 to 25 liters per minute providing a residence time in the electroplating tank of about 10 to 20 seconds. The electroplating tank contains approximately 4.5 liters and the total apparatus (including the containment tank) contains approximately 20 liters. A current density of about 25 ASF was used and the copper bath was maintained in a material balance by removing the electrolyte from the apparatus and adding a copper-containing solution as in Example 1. While the apparatus has been particularly described, present invention, in conjunction with a specific preferred embodiment, it is evident that many alternatives, modifications and variations will be clear to those skilled in the art in light of the foregoing description. Therefore, it is contemplated that the appended claims will encompass any such alternatives, modifications and variations as they fall within the true spirit and scope of the present invention. Having thus described the invention what is claimed is:
Claims (8)
- NOVELTY OF THE INVENTION Having described the invention as above, we consider what is contained in the following: • 5 'CLAIMS 1. An electrolytic method for copper plating a semiconductor substrate of a silicon disk, where the components of the electrolytic bath they are not cumulative and reach a value in a stable state, said method 10 comprises the steps of: providing a plating system comprising a copper plating apparatus comprising a tank and containing a copper electrolyte comprising copper and an additive system for improving the plating properties of the copper and a substrate that it will be veneered as a cathode and a separate insoluble anode; stir the copper electrolyte in the tank, while a current is applied and the cathode is • electroplated; 20 measure the weight of the plated copper; removing a part of the electrolyte from the system when the weight of the plated copper is reached; add to the system, either simultaneously with the withdrawal of the electrolyte or after the removal thereof, so that the volume of the electrolyte in the system is substantially constant, a solution containing the additive system and the copper supply, the solution has a copper concentration greater than the copper concentration of the electrolyte withdrawn and a concentration of • 5 additive greater than the concentration of additive in the removed electrolyte and in an amount sufficient to increase the concentration of copper and the concentration of electrolyte additive in the system to a predetermined value by replacing the copper and additive used in the process of plywood and that are removed in the removed part;
- • And keep the electrolyte volume in the system in a substantially constant volume during electroplating. 2. The method of claim 1, wherein the plating system comprises: a copper plating tank and an electrolyte holding tank, the copper plating tank is preferably cylindrical and has an inlet at the end 20 the tank bottom and an outlet at the upper end of the tank and containing a copper electrolyte and a substrate as a cathode and a separate insoluble anode having a central opening through it, both the cathode and the anode are horizontal, the entrance and exit are placed
- So that the electrolyte current enters the plating tank near the anode and flows through the central opening in the direction of the cathode and out near the cathode; and stir the electrolyte, by circulating the copper electrolyte towards the entrance of the apparatus from the • 5 container tank and simultaneously remove the copper electrolyte from the outlet of the apparatus and direct the copper electrolyte from the outlet to the container tank, while a current is applied and the cathode is electroplated; 3. The method of claim 2, wherein the measured operating parameter is the weight of the plated copper.
- 4. The method of claim 3, wherein the electrolyte and the solution containing the copper are copper sulfate and the copper-containing solution contains an amount of copper between about 70 to 80 g / 1.
- 5. The method of claim 4, wherein the ratio between the anode and the cathode is between about 1: 1 to 4: 1.
- 6. The method of claim 5, wherein the • residence time of the electrolyte in the plating tank 20 copper is less than 1 minute. The method of claim 1, wherein the copper-containing solution is added using a single-use container containing the same amount of solution as the amount withdrawn from the removed part. 8. An apparatus for electrolytic copper plating a semiconductor substrate of a silicon disk, wherein the components of the electrolytic bath are not cumulative and reach a value in a stable state, comprising: an electroplating tank containing the same • 5 a copper electrolyte consisting of copper and an additive system to improve the properties of copper plating, a substrate such as a cathode and a separate insoluble anode, the tank has an input element and an output element; stir the copper electrolyte in the tank at 10 circulating the copper electrolyte through the tank • electroplated from the inlet to the outlet, while a current is applied and the cathode is electroplated; a measuring element for measuring the weight of plated copper; 15 a removal element for removing an electrolyte part of the electroplating tank when the copper weight is reached; and an addition element to add to the electroplating tank, either simultaneously with the removal of the 20 electrolyte or after removal thereof, so that the volume of electrolyte is constant, a solution containing the additive system and the copper supply, the solution has a copper concentration greater than the copper concentration of the electrolyte removed and the The concentration of the additive is greater than the concentration of the additive in the electrolyte removed in an amount sufficient to increase the concentration of copper and electrolyte additive in the system to a predetermined value by replacing the copper and the additive used in the process. • 5 plated and removed in the removed part and to maintain the volume of the electrolyte in the tank at a substantially constant volume during electroplating. The apparatus of claim 8, further comprising an electrolyte holding tank from which 10 the electrolyte is pumped into the electroplating tank and • inside which the electrolyte is pumped out of the electroplating tank. 10. The apparatus of claim 9, wherein the anode is near the inlet and has an opening in the 15 through which the circulating electrolyte passes. 11. The apparatus of claim 10, wherein the. The output element is close to the cathode edge. 12. The apparatus of claim 11, wherein the outlet is a continuous opening around the periphery of the 20 electroplated tank. 13. The apparatus of claim 12, wherein the operation parameter is the weight of the plated copper. 14. A semiconductor product made by the method of claim 1. 15. A semiconductor producer made by the method of claim 5. 16. A semiconductor product made by the method of claim
- 7. 17. The apparatus of the claim 8, wherein the anode has a central opening through it, so that the electrolyte entering the apparatus flows through the opening in the direction of the cathode. 1
- 8. The apparatus of claim 8, wherein the addition element comprises a single-use container containing a copper and additive solution. SUMMARY OF THE INVENTION A plating system and a method for electroplating copper silicon discs using an insoluble anode is provided, wherein the electrolyte is agitated or preferably circulated through an electroplating tank of the system and a portion of the Electrolyte is removed from the system, when a predetermined operating parameter is reached. It is added to the copper plating system, either simultaneously with the removal of the electrolyte or after removal thereof, a solution containing copper having a copper concentration greater than the copper concentration of the removed part, in a substantial amount equal to the electrolyte removed in the current removed. In a method that serves as a reservoir to circulate the electrolyte. The addition of the copper-containing solution and removal of the operating electrolyte is preferably done from the container tank. The preferred apparatus is preferably cylindrical and is specially configured so that the circulating electrolyte enters near the anode and comes out close to the cathode, and the apparatus outlet of the apparatus has a substantially continuous opening around the periphery of the electroplating tank, so that the electrolyte leaving the tank has a substantially uniform flow along the surface of the cathode. The anode is preferably circular and has a central opening through it, through which the incoming electrolyte passes.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08948748 | 1997-10-10 |
Publications (1)
Publication Number | Publication Date |
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MXPA00003455A true MXPA00003455A (en) | 2001-07-31 |
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