TW200918685A - Method and apparatus to prewet wafer surface for metallization from electrolyte solutions - Google Patents

Abstract

The present invention improves wetting between electrolyte solutions and a wafer surface when contacting each other by pre-implementing a liquid adsorption layer on the entire front surface of the wafer prior to a metal disposition process. The pre-implemented liquid adsorption layer is realized by transporting vaporized liquid molecules from vapor phase at an elevated temperature (relative to wafer) and condensing them onto the wafer surface.

Description

200918685 IX. INSTRUCTIONS OF THE INVENTION: TECHNICAL FIELD OF THE INVENTION [0 0 0 2] The present invention relates to surface wetting of wafers for use in electrochemical or chemical deposition of metal layers, and more particularly to pre-wetting wafer surfaces. [0004] Advanced interconnect structures in ultra-large-scale integrated (ULSI) circuits are partially fabricated by electrochemical or chemical (also known as "electr〇lessly") deposition methods from one or more Electrolysis = A metal material, usually copper, is deposited on the surface of the wafer. In the deposition process, a dry wafer is first immersed in an electrolyte solution, or an electrolyte is sprayed onto a dry wafer. However, several problems may be encountered: one of the serious problems is the wafer surface. Incompletely immersed / V by the electrolyte cannot deposit a metal layer where the electrolyte is exposed for a long time. The infiltration-related defects caused by the two mechanisms are usually manifested by the absence of deposited films and the presence of large pores and unfilled knives in 诵$, m+, and grooves. The device is scrapped. Matter: 05] Incomplete wetting between the electrolyte and the wafer is a type of surface and may be caused by a number of factors affecting the surface properties of the electrolyte and the wafer. For example, the compatibility between the surface of the wafer and the electrolyte containing various types: one, the % of the wafer touched by the electric ore or chemical bell yak 2, the aging of the electrolyte, in the process flow The waiting time between the current = step and the previous 1 step, the previous y can be a thin metal layer or ground to make the metal and electricity part of the 200918685 medium exposed. This waiting time is especially important' because the oxidation of the wafer surface during this time can dramatically change the surface properties of the wafer. A method of improving the surface impregnation of a copper-deposited wafer is to perform a pre-wetting step on an electro-chemical deposition apparatus as disclosed in the Japanese Patent Application No. WO 04/9644, and US Pat. According to this method, the wafer is first pre-soaked in a spin-wet-dry (SRD) module using deionized water (DIW). A combination of rotational rate (RPM) and deionized water (DIW) flow fans is used to increase water coverage on the wafer surface. After pre-wetting, the surface of the wafer should carry a thin layer of water when it is immersed in the electrolyte. The addition of a pre-wetting cavity to a metal film deposition apparatus increases its overall size and requires more space to install the corresponding device. [〇m] Another way to achieve the pre-wetting layer is to use a built-in deionized water (DIW) nozzle located in the electric ore processing module (4). (4) such a party

The L method 'DH is ejected onto the wafer surface when the wafer is fixed in the rotating wafer + disk and facing the electrolyte. The centrifugal force causes the diw: to be directly on the surface of the rotating wafer without falling into the electrolyte. Such a method is disclosed in U.S. Patent Application Serial No. 2006/71,46,994. The k榷 method does not require extra space, so the regulation of the whole device, fear, the stability of the method is not good, such as *DIW nozzle has a slight speed to decrease, it will cause DIW to be injected into the electrolyte. . s曰曰[ 0 0 0 8 ] These two methods have three inherent problems: 4"立曰,丄)^Financial I's factory in which each wafer is brought into the electrolyte to cause a plating solution The overall dilution, and then change, ', 曰Η win good art conditions. (2) The water layer in the enamel-coated electrolyte causes the electrolyte in the surface area of the wafer to be diluted by the 200918685 portion, especially the localized dilution of the through-holes and trenches of the metal layer to be deposited by D丨w. The structure of the filling n is formed into a cavity after the electric ore and is not filled () l long process time, well understood 请 - please handle the surface of the wafer can not be separated, because a Rong exhibition to aa ^ Ding Yu The viscous resistance of the water flow in the water layer r ^ ^ _ 4 layer is too large (in inverse proportion to the square of the basin). , /, less; iron, the production of 4 + 曰 and the degree by the burst of minus f :. “To increase the processing time, the whole set of equipment will be affected. It will also have a constant evaporation of each wafer, 'the movement of the machine in a semiconductor production equipment and the priority of the rise' drop to evaporation. The condition and time have an effect. 1 s [〇_] Another method is to reduce the surface tension of the electrolyte by means of a wetting enhancer, generally a surfactant or a group of active agents, such as: Application 帛 20 04/6776 893. Another method of pretreating the surface of the wafer is to pretreat the liquid containing the wetting enhancer in a separate module before placing the wafer in the electromineral electrolyte. The wafer surface is disclosed in U.S. Patent No. 6,875, 260. This method enhances the processing complexity and greatly increases the cost of processing and monitoring. As the surface size of the wafer continues to decrease, as described in the three methods above. The method of pre-wetting the surface of various wafers by replacing the gas with a viscous liquid in the nano-scale trenches is extremely challenging. [Summary of the Invention] [0011] The present invention is to increase the infiltration of the electrolyte and the surface of the wafer in contact with each other by adding a liquid adsorption layer on the front surface of the entire 200918685 sheet before performing the metal deposition process. The pre-set liquid adsorption layer is Liquid molecules at elevated temperatures (relative to the wafer) condense from the vapor phase to the surface of the wafer. [0 012] Pre-wetting is accomplished by a process in which steam is continuously produced to provide vapor in the gas phase, Instead of using a viscous liquid to replace the gas that floods the front side of the wafer, the liquid molecules in the gas phase condense after they reach the surface of the wafer.

[001 3] The vapor is transferred to the wafer surface by a nozzle that is stationary or moving relative to the wafer. The steam is produced by heating a liquid in a pipe under controlled pressure. [0014] Vaporized liquid molecules penetrate into small structures by vapor convection and diffusion, which is very fast compared to liquid permeation affected by surface infiltration behavior and is not affected by solid surface properties; The time required to completely cover the steam on different wafer surfaces is the same [

[Embodiment] [0020] FIG. 1a shows a process for pre-wetting the surface of a wafer for metal rafts. A liquid, such as X M 1 t deionized water, is used to form the liquid adsorbing layer. This liquid will be twisted with cats "β ώ / ... to a predetermined temperature (as shown in step 1200). In one embodiment, the temperature of the liquid will rise to 35»c-1 Between 7 0 C. When raised to a predetermined temperature, w is vaporized (as shown in step 104). The liquid 蒗, version 07 can be π-activated with steam (nash evaporation) Or the carrier gas is flushed to the liquid 200918685. When the liquid is vaporized, the pressure of the vapor is controlled within a certain range (as shown in step 106). The vapor partial pressure of the vaporized liquid is Monitored by the sensor. The vapor containing liquid molecules will be mixed with a carrier gas medium before the liquid molecules are transferred to the wafer surface, such as: air, nitrogen (N2), helium (He), and argon (Ar). (as shown in step 108). When mixing the gas phase liquid molecules with the carrier gas medium, the temperature of the resulting mixture is maintained within a predetermined range (as shown in step 10 0), so at elevated temperatures The formed liquid adsorption layer is formed at room temperature The surface tension of the liquid adsorption layer is small. In the next step, the vaporized liquid molecules will be transported to the surface of the wafer and then condensed to form a thin layer of liquid. According to Figure 1, in step 112, the liquid vaporized molecules and The mixture of carrier gases is delivered to the environment near the surface of the wafer, and in step 114, a large amount of air in the environment of the wafer surface is replaced by liquid vaporized molecules and carrier gas. In step 116, liquid vaporization The molecules are transported from the vapor environment to the patterned structure on the surface of the wafer. In one embodiment, the liquid vaporized molecules are transported to the vias, trenches, and double-embedded structures on the wafer surface by gas relative flow. And a combination of diffusion is achieved. Then, in step 117, a pre-wetting liquid layer is formed on the front surface of the entire wafer by adsorbing the plurality of vaporized liquid molecules from the vapor. In an embodiment, When the surface of the wafer has a distribution of different surface free energies, it is possible to selectively condense vaporized liquid molecules. Surfaces with higher surface free energy The formed liquid adsorption layer can trigger selective nucleation in the subsequent metal layer deposition process. The thickness of the preformed liquid adsorption layer is generally several nanometers, and the thickness thereof is smaller than that in the conventional art by flushing 9 200918685 and rotating The prepreg layer formed by the hydrodynamic action, in the thick sound/liquid adsorption embodiment of the liquid pre-adsorption layer in the conventional art, is 10 μm by the base vapor on the surface of the wafer. The thickness of the liquid adsorption layer in one is subjected to Several factors control, a is the content of liquid molecules that form the surrounding environment to vaporize ^• temperature difference, surface energy, and heat of adsorption on the surface of the wafer. The temperature difference between the vapor and the wafer surface between the wafers When it is not very large, the content of liquid molecules vaporized in the environment around the surface of the surface of the liquid layer by the BET multilayer adsorption isotherm can be adjusted by the liquid molecular vapor depot in the wafer table. Finally, as shown in (4) 虞^ object 120, the sound of the wafer will be in contact with the layer of adsorbed liquid carried on the surface of the step. In an implementation of your 丨Φ money electrolyte 隹贝苑, as shown in optional step 119, the electroplating treatment, before the 盥t solution using the electric au ^ electrolyte contact before a bias voltage can ^ ^ + wafer surface Then, before step 120, the application step is added to the selection step 11, and the stone head, 丨. He adds the bias to the battery. Otherwise, the step 11g can be omitted. The overall electricity caused by the adsorption layer is very thin when the layer is very thin, and the liquid is adsorbed on the surface of the wafer when the liquid electrolyte contacts the surface of the wafer. Liquid 卜, η, > 3 / dilution of mineral electrolytes' even high yield

Month / also very small. For example, the overall dilution percentage of R of 2 too households and the liquid layer with a liquid layer [〇〇 = micro-no plant is 5000 times smaller. In the process, which uses another process for pre-wetting/squeezing the surface of the batt, a liquid is used to treat the vaporized liquid. At step 132, the column is heated as deionized water. Then, in step % n4 + a carrier gas, such as Μ... (4) 任, in step 134 'being (heart)::,), gas (five) and chlorine, 讣) heated liquid, then liquid Steam with load 10 200918685

The body milk is mixed to form a vapor mixture. In step 136, the flow rate of the carrier gas is controlled to adjust the content of liquid vapor molecules in the mixed gas. The pressure of the steam mixture is controlled (as shown in step 138). Step 14〇15〇 is the same as step 11 〇 -1 2 上述 above. That is to say, in step 丨4 ,, the temperature of the mixture is maintained. In step 142, the vaporized liquid molecules are delivered to the environment near the surface of the wafer. In step i44, a large amount of air around the surface of the wafer is replaced by vaporized liquid molecules. In step 146, the π-formed liquid molecules are transferred from the vapor environment to the wafer surface and transferred to the patterned structure. In step i48, the vapor in the vapor environment is condensed to the surface of the wafer to form a liquid adsorbing layer. In step 150, the liquid adsorbing layer carried on the surface of the wafer is in contact with the plating electrolyte. An optional step is provided for the use of a bias voltage when electrochemical plating is used. In another embodiment, the step of vaporizing the liquid can be accomplished by other methods, such as steam excitation (flash evap〇rati〇n). [0 0 22 ] The pre-wetting treatment can be used for semiconductor device interconnection structures or fabrication, in which pre-wetting in the contacts is to be performed in the electrolyte solution, the surface of the sheet, the electrical contacts including the contact blocks ( Fluorescent and used to encapsulate semiconductors. "Niu @ penetration 矽 through-hole structure 不 不 @ metal I deposition step contains different metal elements in the electrolyte, for example, the electrolyte may contain copper (CU) to (AU), silver (Ag), nickel (Ni ), ruthenium (Ru) and cobalt (Co) elements are used in semiconductor devices. • • • • • • • • • • • • • • • • • • • • • • • • 以及 以及 以及 以及 以及 以及 以及 以及 以及 以及 以及 以及 以及The (Sn), flip (Pt), and silver (Α§) elements are used to encapsulate semiconductor devices. The preformed liquid adsorbing layer on the surface of the corona sheet should be wetted and mixed by the electrolyte. 200918685 [0 0 2 3 ] Figure 2 shows an apparatus for carrying out the pre-wetting treatment described above. The apparatus 200 includes a substrate holding device 202 for holding a substrate having one or more patterns thereon. The formed metal layer also covers a portion of the surface of the substrate 2〇4. In one embodiment, the motor 2 〇 3 causes the substrate holding device 2 〇 2 to rotate. The vapor transport unit 206 sprays steam containing at least one molecule of a thin liquid adsorbing layer to be condensed on the surface of the substrate. as shown in picture 2,

The steam delivery device 206 includes: a nozzle or a set of nozzles 2 6 〇, a pipe 2 6 2, a positioner 264, a pressure regulator 26, a partition 268, and a filter 269. A filter 269 is provided in front of the pressure regulator 266 and isolated using a dividing wall 268. A mechanical system 21 is also provided, which consists of a drive 212 and a connecting arm 211 'which control the relative movement between the vapor transport device 206 and the substrate 204. The nozzle 26 is located adjacent the surface of the substrate 204, and the nozzle 26 can be housed in a separate processing module or incorporated into an existing process module, such as the electromine module (e.g., discharge plate 261). If the nozzle 26Q is bonded to the wafer transfer robot arm, the pre-formed liquid adsorption layer of the thin layer can also be formed during wafer transfer. In one embodiment, the nozzle 26(R) may be stationary or may be relatively retarded by the drive. Continuing with Figure 2, the apparatus 200 further includes a steam generating device 2 〇R ^ ^ A v . ^ ^ _ ' which converts a portion of the liquid into steam. As shown in Fig. 2, the steam production 4 μ pull..., the flying seat sigh 208 includes: a conduit 280, a liquid inlet 281, an outlet 282, a pressure 铿 force release valve 283, a throttle valve 284, a heating thief 2 8 5. Pressure temperature control returns 9 Q β Μ 286, carrier gas inlet 287, liquid outflow end 288, and gas outlet 2sq. ° Heat the liquid in the conduit 2 80 under controlled pressure to create a tomb, and I α ° —drying gas, for example: empty 12 200918685 • Gas, nitrogen (N2), helium (He), or argon (Ar) is a carrier carrying vaporized liquid molecules. A dry gas source 29 1 produces a dry gas. Drying • The gas flows into the liquid in the conduit and out of the outlet while carrying the vaporized liquid molecules through a pressure regulator before reaching the nozzle. In one embodiment, the pressure relief valve 283 is disposed between 1 and 7 bar, and the pressure temperature control loop temperature is set between 35 ° C and 170 ° C. The steam delivery line from the steam generator to the nozzle is insulated. The steam outlets on the steam delivery unit 206 can have a variety of orientations and sizes. Fk [0024] The above components: a set of nozzles 260, a pipe 2 62 and a locator 2 6 4 can be built on an existing process module, for example in a metal layer deposition module, directly located in FIG. 2 Shown above the metal deposition chamber containing electrolyte 2000. BRIEF DESCRIPTION OF THE DRAWINGS [0 0 1 6 ] FIG. 1 a is a flow chart of wafer surface pre-wetting treatment according to an embodiment of the present invention; ; ; 〇 [ 0 0 1 7 ] FIG. 1 b according to another aspect of the present invention A flow chart of wafer surface pre-wetting treatment of an embodiment; [0 0 18] FIG. 2 is a schematic view of a wafer surface pre-wetting apparatus according to an embodiment of the present invention. [Main component symbol description] 200. Pre-wetting treatment device 20. Holding device ^ 203. Motor 204. Substrate 13 200918685 . 2 0 6. Steam conveying device 2 10. Mechanical system * 2 1 2. Driver - 2 6 1. Discharge plate 2 6 4. Positioner 268. Isolation wall 280. Conduit 282. Outlet r: k 284_Throttle valve 2 8 6 · Pressure temperature control circuit 2 8 8. Liquid outflow end 290. Electrolyte 208. Vapor generating device 211. Connecting arm 2 6 0. Nozzle 262. Pipe 2 6 6 · Pressure regulator 269. Filter 281. Liquid inlet 2 8 3. Pressure relief valve 2 8 5 . Heater 287. Carrier gas inlet 289. Gas outlet 291 Dry gas source

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Claims (1)

200918685 X. Patent application scope: 1 · A method for pre-wetting the surface of a wafer, comprising: 'steaming a liquid; delivering vaporized liquid molecules to the environment near the surface of the wafer; replacing the environment near the surface of the wafer with vaporized liquid molecules a large amount of air and transport them to the surface of the wafer and into the patterned structure; from the vapor environment, the liquid adsorption layer is condensed on the surface of the wafer including the patterned structure; r, 1 is contacted with the electrolyte to carry the adsorbed liquid The wafer surface of the layer. 2. The method of claim 1, wherein the liquid forming the liquid adsorption layer on the surface of the wafer is wettable by the electrolyte. 3. The method of claim 1, wherein the liquid forming the liquid adsorption layer on the surface of the wafer is mixed by the electrolyte. 4. The method of claim 1, wherein the liquid is vaporized by steam excitation. 5. The method of claim 1, wherein the carrier gas is flushed into the liquid to vaporize the liquid. 6. The method of claim 1, wherein the carrier gas is selected from the group consisting of: 15 200918685 air, nitrogen (N2), helium (He), and argon (Ar). 7. The method of claim 1, wherein the vaporized liquid molecules are transported to the through-holes, trenches, and patterned structures of the wafer surface by vapor phase diffusion and convection bonding. . The method of claim 1, wherein the liquid adsorbing layer is of a nanometer thickness and is formed by multi-layer adsorption of vaporized molecules on the surface of the wafer. 9. The method of claim 1, wherein the content of vaporized liquid molecules in the environment surrounding the surface of the wafer is adjusted by the partial pressure of liquid vapor in the mixture. The method of claim 1, wherein the thickness of the liquid adsorbing layer is controlled by the content of vaporized liquid molecules in the environment around the surface of the wafer. The method of claim 1, wherein the thickness of the liquid adsorbing layer on the surface of the wafer is controlled by a temperature difference between the vapor and the surface of the wafer. The method of claim 1, wherein the surface tension of the liquid adsorbing layer formed at an elevated temperature is smaller than the surface tension of the liquid layer formed at room temperature of 16 200918685. U. The method of claim 1, wherein the vaporized liquid molecules are selectively condensed when the wafer is ^ -s ^ ^ 邱. The method of claim 13, wherein the liquid selectively nucleates. In the following metallization process, the method of claim 1, wherein the method is applied to a wafer surface deposited by a metal layer in a V-body device interconnection structure. - In the electrolyte solution, the method described in item 15 of the second patent range, "the metal ion of the electrolyte A is from the following group of metal salts (Au) 'silver one called one gold = two:: The method of the invention, wherein the surface is infiltrated in the electrolyte solution:::: the surface of the wafer deposited by the pre-K-disc layer during the process of two wires and solder joints. The method, ... the liquid eliminator 'carved in the next one, and to the salt: copper (CU), gold (Au), 17 200918685. Nickel (Ni), strontium (Sn), platinum (Pt) And silver (Ag). The method of claim 1, wherein the method is used to encapsulate a surface of a wafer on which a metal layer is deposited in an electrolyte solution during formation of a through hole of a semiconductor device. 20. The method of claim 19, wherein the metal ion is selected from the group consisting of copper (Cu), f' nickel (Ni), tin (Sn), pin (Pt), and Silver (Ag) 2 i • A device for pre-wetting the surface of a wafer, comprising a substrate holding device 'holding thereon having one or more substrates' - the formed metal layer covers at least the surface area of the substrate; the vapor transport device 'sprays steam containing at least one molecule which will form a thin layer of liquid adsorption layer on the substrate; G steam generating device converts part of the liquid into Steam; mechanical system, controlling the relationship between the steam delivery device and the substrate. 22. The device of claim 21, the material holding device, the steaming device and the mechanical system are in a rational module. The device of claim 2, wherein the pre-wetting is in the middle of the electrolyte (Au), and the surface of the partial portion of the pattern is condensed against the movement. The steaming 18 200918685 steam conveying injury and the mechanical plugging system are combined into the metal deposition module. 2 [If the patent application scope 2 steam conveying device is installed in the device, the 曰 传输 transmission machinery On the arm. 2 5. As described in the application for the patent ~ the preparation of the 21st generation, the steam transmission equipment of Lizhong includes: Μ ^ installed 4 of the filter. Road, clamp, pressure regulator and over 2 6 . Patent Application No. 9 for a vapor transmission device by means of a drive-in device, such as steaming 2 7 · as claimed in the patented material holding device by means of a device, wherein the device is performed by the Kedama motor Rotational operation η 28 . Such as the patent application of the steam generating equipment includes: conduit brother fluid ::: described device ' ” the steam shut-off valve Η, heater, pressure temperature 1 °, pressure relief valve, liquid outflow and Gas outlet. . The road carrier gas inlet, 29, as described in claim 28, the force release valve is disposed between the devices (where the pressure, Dar). 30. The device as claimed in item 28 of the patent application' is at a pressure of 19 200918685 between 3 5 ° C and 170 ° C. The temperature in the temperature control loop is set C 20