TWI228157B - ECP method and apparatus thereof - Google Patents

Abstract

An electrical chemical plating (hereafter ECP) method is employed to deposit Cu layer on a wafer without Cu residues left on the bevel of wafer. A Cu plate is electrically connected to the anode of DC source. A contact ring is electrically connected to the cathode of DC source. The pressure between the bevel of wafer and the contact ring is under a predetermined value. The pressure between non-bevel area of wafer and the contact ring is above the predetermined value.

Description

1228157 _Case No. 92125826_ Year and Day Amendment__ V. Description of the invention (1) [Technical Field to which the Invention belongs] The present invention relates to a method of electroless copper electroplating, and in particular to a chemical suitable for use in semiconductor manufacturing processes. Electroplated steel method. [Previous Technology] In integrated circuits, a method for manufacturing copper wires is to electro-chemically deposit a copper thin film on a deposited copper seed layer by using an electro-chemical plating device. After electroplating, the copper film on the wafer is always peeled off around it, which causes particle contamination or low yield in subsequent processes. Therefore, after the electroless plating process, a process is added to wash the copper film around the wafer to avoid subsequent problems caused by the copper film peeling. In the conventional chemical plating equipment, the equipment manufacturer has designed an integrated edge cleaning module (IBC, Integrated Bevel Clean) to remove the steel film around the wafer. The conventional edging process uses a edging module to spray a solution used to dissolve a copper thin film around the plated wafer after the electroplating, thereby removing the copper thin film. Solutions commonly used to dissolve copper films include a mixture of sulfuric acid, peroxide (H 20 2), and DI water. However, the process of wafer cleaning is often sprayed with a solution that dissolves the copper film. It is inevitable that the solution is sprayed on other parts of the wafer (not the surrounding circle). The copper wires that successfully form a normal integrated circuit are also Destroyed by solution excess. Therefore, integrated circuit manufacturers need an innovative approach to overcome

1228157 _ Case No. 92125826_ Year Month Revision _ 5. Description of the invention (2) Solve the above problems. [Summary of the Invention] Therefore, an object of the present invention is to provide a method for electroless copper electroplating to suppress a copper thin film formed around a wafer after electroplating. Another object of the present invention is to provide an electroless copper electroplating device for suppressing the copper thin film generated around the wafer after electroplating, so that the electroless copper electroplating device does not need the edge cleaning module. According to the above object of the present invention, a chemical plating method is proposed, which is suitable for electroplating a copper film on a wafer, and avoids electroplating the copper film on the periphery of the wafer. In this electroless copper plating method, a copper electrode is connected to the positive electrode of a power source, and a wafer is used to connect a ring-shaped point contact electrode. When performing electroplating, the pressure at the contact surface between the ring-shaped point contact electrode and the surrounding portion of the wafer must be less than a predetermined critical value. The pressure of the contact surface between the ring-shaped point contact electrode and the non-peripheral portion of the wafer needs to be greater than this predetermined critical value. According to another object of the present invention, an electroless copper electroplating device is proposed. This electroless copper electroplating device is electrically connected to a power source, and is suitable for electro-depositing a copper film on a wafer 'to prevent the surrounding of the wafer from being coated with a copper film. The electroless copper electroplating device includes an annular point contact electrode, and the annular point contact electrode contacts the wafer with an IC side. The electroless copper electroplating device further includes a thrust pad to contact the wafer. The thrust pad applies different pressures to the contact surface between the surrounding, non-peripheral portion of the wafer and the ring-shaped point contact electrode respectively, wherein the pressure on the contact surface between the peripheral portion of the wafer and the ring-shaped point contact electrode is less than a predetermined threshold Value between the non-peripheral part of the wafer and the ring-shaped point contact electrode

Case No. 92125826 1228157 said amendment year month 5. Description of the invention (3) The pressure at the contact surface is greater than this predetermined threshold. From the above, it can be known that by applying the chemical plating method of the present invention, the ohmic contact pressure between the plated cathode and the wafer can be used to suppress wafer: peripheral-circle copper film deposition. In addition, the thrust pad and air cushion of the chemical plating equipment of the present invention can be used instead of the edge washing module in the conventional chemical plating equipment. [Embodiment] Please refer to FIG. 1, which illustrates a schematic diagram of a chemical plating principle according to a preferred embodiment of the present invention. The electro-chemical plating method of the present invention is applied to a copper process to form copper wires. Before the electroless plating process, a copper seed layer needs to be formed on the wafer as an electrode, and the copper seed layer is used as a cathode 24 during electroplating. This cathode 24 is connected to the negative electrode 21 of the power source 20. On the other hand, the steel electrode 22 and the anode 19 of the power source 20 are connected. During electroplating, copper ions are dissociated from the copper electrode 22, and the effects of convection and migration of steel ions will move to the vicinity of the cathode 24, and finally di f fusion to the copper seed layer (Cathode) 24 on. In order to remove the copper film around the wafer after electroplating, the method of electroless copper electroplating of the present invention controls the ohmic contact pressure between the cathode of the bond (Cathode) and the wafer to Inhibit copper film deposition around the wafer. In other words, if the ohmic contact pressure between the plated cathode and the wafer is less than a certain threshold value, the copper thin film cannot be deposited on the wafer. Therefore, in the following preferred embodiments, by applying different ohmic contact pressures to the peripheral and non-peripheral parts of the wafer (wafer

Page 9 1228157 _E ^ _92125826 V. Explanation of the invention (4) The ohmic contact pressure around the correction sheet is smaller (the contact pressure is larger) to suppress the copper around the ohmic sheet around the non-peripheral part of the wafer. Thin film sink 2 is a diagram showing the relationship between the thickness of the membrane during a European operation according to the contact pressure and the electroplated copper thin & This figure is a chemical plating relationship diagram. Gum contacted Lili and the thickness of the electroplated copper thin film; 1 means that when the ohmic contact pressure 1 3ds i, the Thunder W domain system line 50 indicates that the ohmic contact pressure is less than the frequency ratio off your green " Vfikh! Film speed. The speed of the electroplated copper film at the relation line 60 is clear. The binocular uses the electroplated copper film speed at the relation line 50, and the peripheral part f of the wafer uses the electroplated steel film speed at the relation line 60. Therefore, when the non-peripheral parts of the wafer have reached the required thickness during the electroplating process, only a thin copper film can be deposited on the outer periphery of the wafer. FIG. 3 is a schematic diagram of a chemical copper electroplating device according to a preferred embodiment of the present invention. This figure illustrates a device applying the above-mentioned chemical copper bell method. This chemical plating apparatus includes a power source 20, an electrolytic solution container 44, an electrolytic solution 46, a copper electrode 48, a ring-shaped point contact electrode 42, a thrust pad 36, and an air cushion base 30. When the chemical electric clock is started, the wafer 40 is placed between the ring-shaped point contact electrode 42 and the thrust pad 36. The ring-shaped point contact electrode 42 is in contact with the wafer 40 and has an IC side. The copper seed layer (not edged out) on the wafer 40 is connected to the power source 20 and the negative electricity 21. Therefore, a copper thin film can be deposited on the copper seed layer. The ohmic contact pressure between the ring-shaped point contact electrode 42 and the wafer 40 is provided by the contact of the thrust pad 36. The function of the air cushion 30 is to control the thrust pad 36 and the wafer 40.

Page 10 1228157 Case No. 92125826 V. Description of the invention (5) The pressure distribution is. The air cushion seat 30 recognizes > bearing 33 by spraying oxygen, and applies pressure to the thrust pad 36. ^ Deposition of copper thin film on the Uir-circle of the pad, the core 4 = Y: wafer 4 ° "〇4 # ^ 30ΛΛ 宓 X η outside > 丄 十 本 丄 r & The sparse surroundings have different purposes. The air cushion 30 is in the surrounding part :: holes 3¼, the degree is sparse, and the pores in the non-peripheral part 32 are denser. It is found that the pressure distribution is used to control the plating. However, the method of applying force is not limited to the above method. When the wafer “0 non-peripheral stings and the ohmic contact pressure between the ring-shaped point contact electrode 42 is greater than = i, and the wafer“ 〇 When the European contact pressure between the electrode and the ring-shaped point contact electrode 42 is less than 13 psi, the present invention can suppress the deposition of the copper thin film on the periphery of the wafer. The principle of not destroying the wafer. = The above-mentioned preferred embodiment of the present invention shows that by applying the electroless copper electroplating method of the present invention, by controlling the ohmic contact pressure between the plated cathode and the wafer, the periphery of the wafer can be fabricated. Copper film deposition on the ring. In addition, the invention adopts the thrust pad and air cushion of the electroplating equipment. It can replace the function of the edge cleaning module in the conventional chemical electroplating equipment. Again, the present invention has been disclosed as i in a preferred embodiment, but it is not intended to limit, this month " anyone who is eager to learn this skill, Without departing from the spirit and scope of the present invention, various modifications and retouching can be made. Therefore, the scope of protection of the present invention is called as defined by the scope of the attached patent application.

1228157 _ Case No. 92125826_ Year Month Amendment _ Brief Description of the Drawings [Simplified Description of the Drawings] In order to make the above and other objects, features, and advantages of the present invention more comprehensible, a preferred embodiment is given below, In conjunction with the accompanying drawings, the detailed description is as follows: FIG. 1 is a schematic diagram illustrating a principle of chemical plating according to a preferred embodiment of the present invention; FIG. 2 is a schematic diagram illustrating a method according to a preferred embodiment of the present invention. The relationship between the ohmic contact pressure and the thickness of the electroplated copper film; and FIG. 3 is a schematic diagram of a chemical copper electroplating device according to a preferred embodiment of the present invention. [A brief description of the representative symbols of the components] 1 9: positive pole 2 0: power supply 2 1 '· negative pole 3 0: air cushion 3 2: non-peripheral air hole 3 3: air cushion 3 4: peripheral air hole 3 6: thrust pad 3 8: thrust pad Pressure on wafer 4 8: Copper electrode

Page 12 Case No. 92125826 Rev. 1228157 Brief description of the drawing 4 0: Wafer 42: Ring-shaped point contact electrode 4 4: Electrolyte container 4 6: Electrolyte 5 0/6 0: Relationship line

Page 13

Claims (1)

1228157 Case No. 92125826 Amendment VI. Patent application scope Wafer required for electro-forging area is the non-peripheral part of the wafer. 6 A method of electroless copper electroplating, applicable to electroplating copper thin film on a wafer. The copper electroplating method includes at least the following steps: electrically connecting a positive electrode of a power source with a pure copper sheet placed in an electrolyte, electrically connecting a negative electrode of the power source with a ring-shaped point contact electrode, and the ring-shaped point The contact electrode is in contact with the wafer; the wafer is immersed in the electrolyte together with the wafer-shaped point contact electrode to perform a process of electroless copper electroplating; and a pressure greater than 23 psi is applied to the wafer to contact the ring-shaped point The contact surface between the electrodes is used to start the copper electroplating process, and the contact surface between the wafer and the annular point contact electrode is applied under a pressure of less than 13 psi to stop the copper electroplating process. 7. The chemical copper electroplating method as described in item 6 of the scope of patent application, further comprising applying a pressure to a contact surface between the wafer and the ring-shaped contact electrode by applying a thrust pad. 8. The method of chemical electric ore copper as described in item 6 of the scope of the patent application, further comprising applying pressure from the gas emitted from a gas holder to the thrust pad. 9. The method of chemical electroplating of copper as described in item 6 of the scope of patent application, further comprising applying a pressure greater than 23 psi to the area of the electric ore required by the wafer and the: Page 15 1228157 _Case No. 92125826_ Amendment Month_ Sixth, the scope of the patent application contacts the contact surface between the electrodes, electroplated copper film, and a pressure of less than 13 psi is applied to the wafer without plating area and the ring Point the contact surface between the electrodes to suppress the electroplated copper film. 10. The method of electrolessly plating a copper thin film according to item 9 of the scope of patent application, further comprising applying a pressure to a contact surface between the wafer and the ring-shaped point contact electrode through a thrust pad. 11. The method of electroless copper electroplating thin film as described in item 9 of the scope of patent application, further comprising spraying different pressure gas on the thrust pad through the denseness of the air-jet holes on an air cushion. 12. An electroless copper electroplating device, which is suitable for electroplating copper thin film on a wafer, and will not be coated around the wafer. The electroless copper electroplating device includes at least: a power source; an electrolyte container, which contains electrolysis A copper electrode connected to the positive electrode of the power supply, the copper electrode placed in the electrolyte of the electrolyte container; a ring-shaped point contact electrode connected to the negative electrode of the power supply, the ring-shaped point contact electrode contacting the crystal A circle and a thrust pad contact the wafer and apply different pressures to the contact surfaces between the periphery, non-peripheral portions of the wafer and the ring-shaped point contact electrode, wherein the ring-shaped point contact electrode and the wafer The pressure of the contact surface between the surrounding parts should be less than Page 16 1228157 _Case No. 92125826_ Year Month Date__ VI. The scope of patent application is a predetermined threshold. The pressure on the contact surface between the annular point contact electrode and the non-peripheral portion of the wafer must be greater than the predetermined value. Critical value. 1 3. The chemical copper electroplating device described in item 12 of the scope of patent application, further comprising an air cushion, which is applied to the thrust pad by air jet, and then the wafer and the ring are applied by the thrust pad. Point the contact surface between the electrodes. 14. The electroless copper electroplating device as described in item 12 of the patent application range, wherein the threshold value ranges from 13 psi to 23 psi. 15. An electroless copper electroplating device, which is electrically connected to a power source, is suitable for electroplating copper thin films on a wafer and will not be coated around the wafer. The electroless copper electroplating device includes at least: a ring-shaped point A contact electrode is connected to the negative electrode of the power supply, the ring-shaped point contact electrode is in contact with the wafer; and a copper electrode is connected to the positive electrode of the power supply; and a thrust pad is in contact with the wafer and applies different pressures to the crystal The contact surface between the surrounding, non-peripheral portion of the circle and the annular point contact electrode, wherein the pressure at the contact surface between the annular point contact electrode and the surrounding portion of the wafer needs to be less than a predetermined critical value, the annular point The pressure of the contact surface between the contact electrode and the non-peripheral portion of the wafer needs to be greater than the predetermined threshold. 16. The chemical copper electroplating device described in item 15 of the scope of patent application, further comprising an electrolyte container. Page 17 1228157 _Case No. 92125826_ Year and Month Amendment_ VI. Patent Application Range 1 7. The chemical copper electroplating device described in item 15 of the patent application range also includes an air cushion, which is applied by air jet The thrust pad is then urged by the thrust pad to a contact surface between the wafer and the annular point contact electrode. 1 8. The electroless copper electroplating device according to item 15 of the scope of patent application, wherein the threshold value ranges from 13 psi to 23 psi. 1 9. An electroless copper electroplating device, which is electrically connected to a power source, is suitable for electroplating copper thin films on a wafer and will not be coated around the wafer. The electroless copper electroplating device includes at least: a ring-shaped dot A contact electrode connected to the negative electrode of the power supply, the ring-shaped point contact electrode contacting the wafer; and a copper electrode connected to the positive electrode of the power supply; an air-bearing block containing peripheral and non-peripheral portions; and a thrust The pad is in contact with the wafer. With the dense and dense distribution of the air holes around the air cushion base and the non-peripheral parts, different pressures are applied to the thrust pad, and then different pressures are applied to the periphery of the wafer by the thrust pad. The contact surface between the non-peripheral portion and the annular point contact electrode, wherein the pressure between the peripheral portion of the wafer and the contact surface between the annular point contact electrode is less than a predetermined threshold value, and the non-peripheral portion of the wafer The pressure of the contact surface between the part and the ring-shaped point contact electrode is greater than the predetermined threshold. 2 0. The electroless copper electroplating device described in item 19 of the scope of patent application, including Page 18 1228157 Page 19