KR20020030742A - Methods for wet processing electronic components having copper containing surfaces - Google Patents

Abstract

The present invention provides a wet processing method for an electronic component having a surface containing copper. In the method of the present invention, the copper-containing electronic component is contacted with a copper oxidizing solution containing an oxidizing agent and then with an etching solution. The process of the invention is particularly useful for cleaning copper containing parts.

Description

METHODS FOR WET PROCESSING ELECTRONIC COMPONENTS HAVING COPPER CONTAINING SURFACES}

Cross-References to Related Applications

The present invention claims the benefit of US Provisional Application No. 60 / 135,267, filed May 21, 1999, which is incorporated by reference in its entirety.

Field of invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for wet processing electronic components having a surface containing copper. The method of the present invention is particularly useful for cleaning such copper-containing electronic components.

Background of the Invention

BACKGROUND OF THE INVENTION Wet processing of electronic components such as semiconductor wafers, flat panels, and other electronic component precursors is widely used in the manufacture of integrated circuits. Preferably, the wet processing comprises diffusion of electronic components, ion implantation, epitaxial growth, chemical vapor deposition, and hemispherical silicon grain growth, or a mixture thereof. It is done to prepare a processing step such as a process. During wet machining, electronic components come in contact with various processing fluids. The processing liquid can be used, for example, for etching, photoresist removal, cleaning or rinsing of electronic components. See, eg, Berkman et al. And European Patent EP 0 233 184 of the shared patentee; US Patent No. 4,577,650; No. 4,740,249; 4,738,272; 4,856,544; 4,633,893; 4,633,893; 4,778,532; 4,778,532; And US Pat. No. 4,917,123, Handbook of Semiconductor Wafer Cleaning Technology (Werner Kem Edit, published by Noyes Publication Parkridge, New Jersey, 1993), 111-151, the entire disclosure of the Aqueous Cleaning Process.

There are several types of systems available for wet machining. An electronic component may be, for example, a single vessel system isolated from the outside (eg, a Full-Flow ™ system from CFM Technology), a single vessel system open to the outside, or multiple openings with multiple sets open to the outside. It can be processed in a bath system (eg wet bench).

After the process, the electronic component is generally dried. The semiconductor substrate can be dried in a variety of ways as long as it is guaranteed that no contamination occurs during the drying process. Drying methods include evaporation, centrifugal force in a spin-rinser-dryer, chemical or steam drying of the wafer, and include, for example, the apparatus and methods disclosed in US Pat. Nos. 4,778,532 and 4,911,761. .

Regarding the wet processing method used to clean electronic parts, most of them are silicon, and aluminum, silicon oxide, silicon nitride, titanium-containing compounds such as titanium or titanium nitride, tungsten-containing compounds such as tungsten or tungsten silicide, cobalt silicide or these Many efforts have been made to find suitable cleaning processes for electronic components made from small amounts of other components, such as mixtures. "Washing" means a process for removing contaminants such as particles, wax, organics such as residual polish or grease, or other contaminants such as oxide layers attached to the surface of electronic components.

In silicon-containing electronic components, it is known that contacting an electronic component with a "SC1 solution" followed by a "SC2 solution" before the metallization step of applying the metal to the electronic component is very effective for cleaning the silicon-containing electronic component. . In addition, the silicon-containing electronics may be contacted with an aqueous hydrofluoric acid solution to enhance cleaning prior to contacting the SC1 solution.

The SC1 solution is an aqueous solution of hydrogen peroxide and ammonium hydroxide, and the concentration is usually in the range of volume ratio of H ₂ O: H ₂ O ₂ : NH ₄ OH from 5: 1: 1 to 200: 1: 1. The SC1 solution is believed to be washed through the surface oxidation / etching mechanism. For example, hydrogen peroxide creates an oxide layer on the surface of a silicon-containing electronic component, while ammonium hydroxide simultaneously removes or etches oxides formed on that surface. Eventually, a stable state is reached in which a relatively thin (eg, about 1 mm) oxide layer is simultaneously formed and etched on the surface. Particles and other contaminants adhered by the generation and etching of such oxides are liberated. Once liberated, particles and other contaminants can be washed away from the surface of the electronic component.

The SC2 solution, in contact with the SC1 solution and then in contact with the silicon-containing electronic component, includes hydrogen peroxide, hydrochloric acid, and water. The concentration of the SC2 solution is usually in the range of volume ratio of H ₂ O: H ₂ O ₂ : HCl from 5: 1: 1 to 1,000: 0: 1. The SC2 solution is used to remove metal deposits (eg, iron, aluminum, and copper precipitates) that occur while the electronic component is in contact with the SC1 solution. Metal precipitation is not a major problem these days because the purity of the chemicals in the SC1 solution is improved, and the SC2 treatment step is often omitted.

If the surface of the electronic component is treated to contain a metal such as aluminum, the use of the wet processing aqueous solution is drastically reduced. For example, many metals, such as aluminum, are severely corroded when in contact with aqueous solutions. As a result, wet processing of metal-containing electronic components is usually performed using a solvent instead of an aqueous solution. However, the use of solvents is not preferred because of the increased safety risks such as flammability and environmental issues such as recycling or disposal of solvents.

Recently, electronic component manufacturers have begun to use copper instead of aluminum for electronic components. The need to replace aluminum with copper is primarily due to the low resistivity of copper. Copper also has the advantage of having improved corrosion resistance. However, much is not known about washing electronic components containing copper with an aqueous solution.

Maladi, US Pat. No. 4,714,517 et al. (Hereinafter referred to as "maladi") discloses a study of copper partial cleaning used for tape automated bonding (TAB) of semiconductor devices. Maladi processes include dipping the copper portion in a caustic bath and contacting the copper portion with organic weak acids such as citric acid, tartaric acid, and the like. However, maladi does not present a way to control copper etching during cleaning.

The present invention provides an additional method for the wet processing of electronic components having copper containing surfaces. The wet processing method of the present invention preferably uses a conventional solution generally used for wet processing of silicon electronic components. The method of the present invention is particularly useful for controlling the amount of etching of copper placed on an electronic component while simultaneously removing particulate contamination from the surface of the copper-containing electronic component.

Summary of the Invention

The present invention provides a wet processing method for an electronic component having a copper-containing surface. The method of the present invention comprises contacting a surface of an electronic component with a copper oxidizing solution at a first contact point; Contacting the surface of the electronic component with the etching solution at the second contact timing; Steps. The etching solution is maintained in an aqueous solution of pH 5 or less, and includes an etchant and up to 5,000 ppb of dissolved or dispersed oxygen. Contacting the surface of the electronic component with the copper oxide solution and the etching solution removes contaminants from the surface of the electronic component. The use of the two step process described above provides for metal removal and / or corrosion control during the wet processing of copper containing electronic components.

In a preferred embodiment, the present invention provides one or more electronic components in a single container; Filling the vessel with a copper oxidation solution of an oxidizing agent; A method of wet machining an electronic component having a copper-containing surface comprising the step of contacting the electronic component with the copper oxidizing solution at a primary contact time and removing the copper oxidizing solution from the vessel. The method also further comprises filling the vessel with a hydrofluoric acid solution having a pH of 5 or less and containing dissolved or dispersed oxygen of 5,000 ppb or less; Contacting the electronic component with the hydrofluoric acid solution at a second contact time and removing the hydrofluoric acid solution from the container, wherein contacting the surface of the electronic component with the copper oxidizing solution and the hydrofluoric acid solution causes Contaminants are removed from the surface of the part.

Brief description of the drawings

1 is a bar graph showing the percent particle removal of an electronic component having a copper containing surface treated according to the processes of Comparative Examples 1-4 and 5.

Detailed description of the invention

The present invention provides a method for wet processing an electronic component having a surface containing copper. The method of the invention is particularly useful for cleaning electronic components for removing contaminants such as, for example, oxide layers, greases, polishes, organic compounds or particles attached to the surface of the electronic components.

The method of the present invention is useful in any wet process where cleaning of electronic components having copper containing surfaces is required. "Wet processing" means contacting an electronic component with one or more liquids (hereinafter referred to as "processing liquid") in order to process the electronic component in a preferred manner. For example, it may be required to process the electronic component to remove, etch or clean the photoresist from the surface of the electronic component. It may be required to wash electronic components between such processing steps. Wet processing may also include contacting the electronic component with a gas, vapor, or other fluid, such as a vapor or a liquid mixed with the gas, or a mixture thereof. The term "fluid" as used herein includes liquids, gases, vapor phase liquids, or mixtures thereof. In general, such wet machining is done to prepare copper-containing electronics for processing steps such as chemical vapor deposition of a dielectric, plasma etching, or reactive ion etching, or a combination thereof.

There are several types of processing fluids used in the wet process. In general, the most common types of processing fluids used in wet processing are chemical treatment fluids or fluids, and rinsing liquids or fluids. As used herein, "chemical treatment liquid" or "chemical treatment fluid" is any liquid or fluid that reacts with the surface of the electronic component in any way to alter the surface composition of the electronic component. For example, chemical treatment liquids or fluids have the activity of removing contaminants chemically bound or attached to the surface of the electronic component, such as particles, metals, photoresists, or organic compounds, or etching the surface of the electronic component. Or an activity of generating an oxide layer on the surface of the electronic component. Chemical treatment liquids usable in the present invention include one or more chemical reagents to achieve the desired surface treatment. The concentration of such chemical reagent is preferably at least 1,000 ppm, more preferably at least 10,000 ppm by weight of the chemical treatment fluid. It is also possible that the chemical treatment fluid comprises 100% of one or more chemical reagents. Examples of chemical treatment fluids that can be used in the process of the invention are described in more detail below.

As used herein, "rinse liquid" or "rinse fluid" refers to particles that have come off or loosened from distilled water or electronic components and / or vessels by residual chemical fluid, reaction by-products, and / or chemical treatment steps. Or any other liquid or fluid that removes other contaminants. Rinsing liquids or fluids can also be used to prevent re-sedimentation of particles or contaminants that fall off electronic components or containers. Examples of rinsing fluids usable in the method of the invention are described in more detail below.

As used herein, the "chemical treatment step" or "wet processing step" means that the electronic component is in contact with the chemical treatment fluid or the processing liquid, respectively.

"Electronic component having a copper-containing surface" means an electronic component preferably having a surface covered with at least about 0.1 percent copper relative to the total surface area of the electronic component. The copper thickness of the surface is preferably at least about 0.1 microns, more preferably from about 0.5 to about 5 microns. Thus, the electronic component is partially covered with copper. If partially covered, the electronics may be covered with copper in a patterned fashion. Examples of electronic components having a surface comprising copper include semiconductor wafers, flat panels, and other components (ie, integrated circuits) used in the manufacture of electronic components; CD ROM disks; Hard drive memory disk; Or a multichip module.

In the wet machining method of the present invention, an electronic component having a copper-containing surface is contacted with a copper oxidation solution, followed by an etching solution containing up to 5,000 ppb of dissolved or dispersed oxygen. While not intending to be bound by theory, the copper oxide solution oxidizes the copper containing surface (eg, Cu ⁰⁺ to Cu ²⁺ ) to form a thin layer composed of copper oxide or a combination with other copper oxides (eg For example, 1.0 nm or less). The etching solution is believed to etch this copper oxide layer at a controlled rate.

The copper oxidation solution in contact with the electronic component is any liquid capable of oxidizing copper located on the surface of the electronic component. The copper oxidation solution preferably does not contain a chemical to etch copper. The copper oxidation solution is preferably maintained at a pH of at least about 7 or more, more preferably at least about 8 or more to prevent etching of copper. In order to maintain the copper oxidation solution at the pH described above, the copper oxidation solution is preferably not included in an amount such that the acid (eg, HCl, HF, nitric acid) drops below pH 7.

Suitable copper oxidation solutions include, for example, solutions containing oxidants such as hydrogen peroxide, ozone, iron cyanide, or mixtures thereof. The oxidant is preferably hydrogen peroxide. Such oxidants are preferably dissolved or dispersed in compatible liquids such as, for example, non-oxidized organic solvents such as water, basic aqueous solutions, or fluorinated hydrocarbons, or mixtures thereof. It is also possible that the oxidant is a liquid which does not need to dissolve the oxidant into a liquid. Preferably, the oxidant is dissolved or dispersed in water.

The concentration of the oxidant in the copper oxidizing solution depends on the oxidant selected. In general, however, the copper oxidation solution preferably comprises from about 0.1 volume percent to 100 volume percent, more preferably from about 10 volume percent to about 70 volume percent of the oxidant relative to the total volume of the solution. In the case of hydrogen peroxide, the concentration of hydrogen peroxide in the copper oxidation solution is preferably from about 0.1 volume percent to about 10 volume percent, more preferably from about 0.2 volume percent to about 1.0 volume percent relative to the total volume of copper oxidation solution. In the case of ozone, the concentration of ozone in the copper oxidation solution is preferably from about 10 ppm to about 50 ppm, more preferably from about 10 ppm to about 40 ppm.

In a preferred embodiment of the invention, the copper oxidation solution has a volume ratio of H ₂ O: H ₂ O ₂ : NH ₄ OH, preferably from about 5: 1: 1 to about 200: 1: 1, more preferably about 50 SC1 solution from 1: 1 to about 150: 1: 1, and most preferably from about 90: 1: 1 to about 110: 1: 1.

The copper oxidation solution may further include other additives in addition to the oxidizing agent to enhance the wet processing. For example, the copper oxidation solution may also include surfactants, anticorrosive agents, or other traditional additives commonly added to wet processing solutions used for washing. Such other additives are preferably present in the copper oxidation solution in amounts of up to about 5.0 vol%, more preferably from about 0.01 vol% to about 1.0 vol%.

If the surfactant is preferably included in the copper oxidation solution, the surfactant is present in an amount of preferably about 1% by volume or less, more preferably about 0.5% by volume or less relative to the total volume of copper oxidation solution. Examples of surfactants that can be used are, for example, Kirk-Othmer Concise Encyclopedia of Chemical Technology, published by John Wiley & Sons, NY, 1985, pages 1142 to 1144 and detergents of McCarthy. And anionic, nonionic, cationic, and amphoteric surfactants disclosed in McCutcheon's Detergents and Emulsifiers, 1981 North American Edition, MC Publishing, Glen Rock, NJ 1981, the entirety of which is incorporated by reference. Preferred surfactants for use in the present invention include the alkaline NCW601A surfactant and to Tech社(Valtech Corporation, Pughtown, PA) VALTRON ^® SP2275 and VALTRON ^® surfactants, Wako社(Wako Company), such as the SP2220.

If the anticorrosive agent is preferably included in the copper oxidation solution, the anticorrosive agent is present in the copper oxidation solution in an amount of about 0.1% to about 1.0% by weight relative to the total weight of the copper oxidation solution. Examples of anticorrosive agents that can be used include such as benzotriazole.

The electronic component is preferably in contact with the copper oxide solution for a sufficient contact time to form a uniform copper oxide layer over the wafer and to remove some particles due to oxidation of copper and dissolution of copper oxide. Here, "contact time" means the time for which the electronic component is exposed to the processing liquid. For example, the contact time may be a time when the electronic component is exposed to the processing liquid while the container is filled with the processing liquid or the electronic component is immersed in the processing liquid; Time the electronic component is immersed in the processing liquid; And the time for which the electronic component is exposed to the processing liquid while the processing liquid or the electronic component is removed from the container.

The actual contact time chosen depends on factors such as the oxidant present in the copper oxidizing solution, the concentration of the oxidant and the temperature of the copper oxidizing solution. However, the contact time is preferably at least 30 seconds and 10 minutes or less.

The temperature of the copper oxidizing solution during contact is the temperature at which decomposition of the oxidant is prevented in the copper oxidizing solution. The temperature of the copper oxidation solution is preferably 60 ° C. or less, more preferably from about 20 ° C. to about 40 ° C.

Contact with the copper oxidizing solution of the electronic component can be done by any known wet processing technique, and most depends on the selected wet processing system. For example, one or more electronic components may be immersed in a bath of copper oxidizing solution and then dried. Instead, the electronics may be placed in a container, and the copper oxide solution may be poured into the container to fill the container with the solution for contact. The contact may be a dynamic condition (e.g., a condition in which a solution is continuously added to a container containing an electronic component), a static condition (e.g., a condition in which an electronic component is immersed in a solution), or a mixed condition (e.g., Pouring the solution into the container for a period of time, and then immersing the electronic component in the solution for a period of time). Suitable wet processing systems for contacting electronic components are described in greater detail below.

After contacting the electronic component with the copper oxidation solution, the electronic component is contacted with the etching solution. Etching solutions are all liquids, including etchant capable of etching oxidized copper. Preferably, the etch solution includes one or more non-oxidizing acids (eg, acids that do not oxidize copper) that maintain the etch solution at about pH 5 or below. The amount of etchant present in the etching solution is such that the pH of the etching solution is preferably maintained at about 5 or less, more preferably about 4 or less and most preferably about 3 or less. Examples of non-oxidizing acids usable in the present invention include hydrochloric acid; Sulfuric acid; Hydrofluoric acid; Phosphoric acid; Organic acids such as acetic acid, citric acid, or tartaric acid; Or mixtures thereof. As the liquid in which the etchant is dissolved or dispersed, water is preferable, but an organic solvent such as ethylene glycol, propylene carbonate, or methanol, or a mixture thereof may be used.

In a preferred embodiment of the invention, the etching solution is a hydrofluoric acid solution. The hydrofluoric acid solution may include hydrofluoric acid, buffered hydrofluoric acid, ammonium fluoride, or other materials that generate hydrofluoric acid in the solution, or mixtures thereof. Hydrofluoric acid has a volume ratio of H ₂ O: HF in the hydrofluoric acid solution, preferably from about 5: 1 to about 1,000: 1, more preferably from about 100: 1 to about 800: 1, most preferably about 200 Present in an amount from 1 to about 600: 1.

In the present invention, it is preferred that the etching solution is maintained under conditions that promote a slow and controlled etching rate (eg, preferably about 10 nm / min of copper, more preferably about 1 nm / min or less). Found. It is desirable to have a slow and controlled etching rate of copper, so that only the minimum amount of copper needed to clean the electronics is removed. Factors affecting the copper etch rate include the concentration of the etchant in the etching solution, the pH of the etching solution, the amount of dissolved or dispersed oxygen or other oxidant in the etching solution, and the temperature of the etching solution. For example, the etch rate of copper is reduced by decreasing the concentration of etchant, dissolved or dispersed oxygen, and other copper oxidants in the etching solution, increasing the pH, and decreasing the temperature of the solution. Of the above factors affecting the copper etch rate, the amount of oxygen or other copper oxidant dissolved or dispersed in the etch solution most probably affects the copper etch rate. This is because oxygen or other copper oxidants react with copper to form copper oxide, which is easily etched at the pH of the etching solution.

Oxygen dissolved or dispersed in the etching solution is preferably maintained at a concentration of preferably 5,000 ppb or less, more preferably 100 ppb or less and most preferably as low as possible relative to the total weight of the etching solution. In addition, other copper oxidants (oxidants such as those used in copper oxidizing solutions: for example H ₂ O ₂ ) are preferably maintained at 5,000 ppb or less, more preferably 100 ppb or less and most preferably at as low a concentration as possible. do. As noted above, keeping dissolved or dispersed oxygen or other copper oxidant at such low levels decreases the etch rate of copper and ultimately controls the etch.

As mentioned above, the etching solution is preferably maintained at a pH of 5 or less, more preferably a pH of 4 or less, and most preferably a pH of 3 or less. To help maintain the pH within the above ranges, a buffer may be added in addition to the etchant in the etching solution. The buffer is preferably added in an amount sufficient to maintain the pH in the above range. The buffer is present in the etching solution in an amount of preferably from about 0.01% to about 5.0%, more preferably from about 0.05% to about 0.5% by weight relative to the total weight of the etching solution.

In a preferred embodiment of the invention, the etching solution comprises hydrofluoric acid and hydrochloric acid. Hydrochloric acid is desirable because it helps to lower the pH and positively elevate the zeta potential of the surface. The hydrochloric acid is preferably in a volume ratio of H ₂ O: HCl per volume part of hydrofluoric acid in the etching solution, from about 50: 1 to about 1,000: 1, more preferably from about 500: 1 to about 500: 10. Preferably from about 500: 3 to about 500: 7.

The etching solution may also include other additives in addition to the etchant to enhance wet processing. For example, the etching solution may also include surfactants, anticorrosive agents, or other traditional additives commonly added to wet processing solutions used for cleaning. Preferably, such other additives are present in the etching solution in an amount as described above for the copper oxide solution.

The electronic component is preferably in contact with the etching solution for a contact time sufficient to remove oxides generated while the electronic component is in contact with the copper oxidation solution. The actual contact time chosen depends on factors such as the concentration of etchant and dissolved or dispersed oxygen in the etching solution, the pH and temperature of the etching solution and the type of etchant used. However, the contact time is preferably at least 30 seconds and not more than 2 minutes. The temperature of the etching solution during contact is the temperature at which the etching is controlled and attains a slow etch rate (eg, about 10 nm / minute or less). The temperature of the etching solution is preferably 50 ° C, more preferably about 20 ° C to about 30 ° C.

The contact with the etching solution of the electronic component may be performed by any of the above-described wet processing techniques in contact with the copper oxide solution of the electronic component. For example, one or more electronic components may be immersed in a bath containing etching solution and then dried. Alternatively, the electronic component may be placed in the container, and the etching solution may be poured into the container to fill the container with the solution for contact. Also, the contact can be done under dynamic conditions, static conditions, or mixed conditions of both conditions.

In a preferred embodiment of the present invention, in order to minimize the concentration of dissolved or dispersed oxygen, contact of the electronic component with the etching solution is performed in an environment in which the electronic component and the etching solution are isolated from an oxygen source such as air. This isolation can be done by wet processing in a system covered with an external environment and shieldable system (described in more detail below) or with a stable gas such as nitrogen or an inert gas such as argon.

In addition, copper is susceptible to reoxidation after being treated with an etching solution, so that any fluid (eg, chemical treatment or rinsing) that contacts the electronic component after it has been in contact with the etching solution is dissolved or dispersed in oxygen or other. Copper oxidants (eg oxidants used in copper oxidizing solutions) should be included at low levels. Such fluids preferably contain about 500 ppb or less, more preferably 50 ppb or less, and most preferably, low levels of dissolved or dispersed oxygen relative to the total weight of the fluid. Such fluids preferably comprise other copper oxidants of about 500 ppb or less, more preferably 50 ppb or less, most preferably no. By including low levels of dissolved or dispersed oxygen and other copper oxidants in such fluids, the risk of reoxidizing the surface of the electronic component after treatment with the etching solution is significantly reduced.

In addition to contacting the electronics with copper oxidizing and etching solutions, the electronics can be contacted with several other chemical treatment fluids (eg, gas, liquid, vapor or mixtures thereof) to achieve the desired results. For example, an electronic component may include a chemical processing fluid (hereinafter referred to as an etching fluid) used for etching, a chemical processing fluid (hereinafter referred to as an oxide generating fluid) to form an oxide layer, and a chemical processing fluid to remove a photoresist (hereinafter referred to as a photoresist). Contact fluid), chemical treatment fluid to enhance cleaning (hereinafter referred to as cleaning fluid), or mixtures thereof. Electronic components may also be rinsed with rinsing fluid at any point during the wet process. The chemical treatment fluid and the rinse fluid are preferably liquid.

It will be apparent to those skilled in the art that various types of processing fluids can be used during wet processing. Examples of other processing fluids that can be used during wet processing are “chemical etching” of Werner Kern, among thin film processes (edited by Thinner Film Process, edited by John L. Vosser et al., Published by Academic Press, NY 1978, pp. 401-496). The contents of the above are incorporated by reference in their entirety.

In addition to contacting the electronics with the chemical treatment fluid, the electronics may also be in contact with the rinsing fluid. As noted above, rinsing fluids are used to remove residual chemical treatment fluids, reaction by-products, and / or loose particles or other contaminants that have come out of the electronic components and / or vessels by chemical treatment steps. Rinse fluid may also be used to prevent particles or contaminants from reattaching to electronic components or containers.

Any rinse fluid that is effective to achieve the above effects can be selected. In selecting a rinse fluid, factors such as the surface properties of the electronic component to be rinsed, the nature of the contaminants dissolved in the chemical treatment fluid, and the nature of the chemical treatment fluid to be rinsed should be considered. In addition, the preferred rinsing fluid should be compatible (ie relatively non-reactive) with the materials that occur during contact with the fluid. Usable rinse fluids include, for example, water, organic solvents, vessel solvent mixtures, or mixtures thereof. Preferred organic solvents include organic compounds used as drying liquids to be described below, such as C ₁ to C ₁₀ alcohols, preferably C ₁ to C ₆ alcohols. Preferred rinse fluids are liquids and contain low levels of oxygen (eg, preferably up to 5,000 ppb, more preferably up to 500 ppb, most preferably up to 100 ppb). In the most preferred embodiment the rinsing fluid is deionized water.

The rinsing fluid may also optionally include low levels of chemical reagents to enhance rinsing. For example, surfactants and / or anticorrosive agents can be used in the rinsing fluid. The concentration of such additives in the rinsing fluid is very low. For example, the concentration is preferably about 1,000 ppm by weight or less, more preferably 100 ppm by weight or less relative to the total weight of the rinsing fluid.

It is apparent to those skilled in the art that the choice of chemical treatment fluid and the order of the chemical treatment fluid and the rinsing fluid depend on the desired wet processing results. For example, the electronic component may be contacted with a rinsing fluid before or after one or more chemical treatment steps. Instead, it may be desirable in some wet processes that the electronic component does not come into contact with the rinse fluid between the two chemical treatment steps (ie, without intermediate rinsing), and that the next chemical treatment step is followed by one chemical treatment step. . Such intermediate rinse-free continuous wet processes are disclosed, for example, in US patent application Ser. No. 08 / 684,543, filed Jul. 19, 1996, which is incorporated by reference in its entirety.

In addition, as in one embodiment of the present invention, it is preferable to wet the surface of the electronic component by contacting the electronic component with a rinsing fluid such as deionized water before contacting the electronic component with the copper oxidation solution. In this wet processing step, the rinse fluid is preferably at a temperature of about 20 ° C to about 60 ° C, more preferably about 20 ° C to about 40 ° C. It is also desirable to add a surfactant to this rinse fluid, preferably at the level described above for the copper oxidizing solution.

In another embodiment of the present invention, after contacting the electronic component with the copper oxidation solution, the electronic component is contacted with a rinsing fluid before the electronic component is contacted with the etching solution. The rinse fluid is preferably deionized water, which is at a temperature of about 20 ° C to about 60 ° C. The rinsing fluid also preferably contains low levels of oxygen as described above. The electronic components are preferably in contact with the rinsing fluid for a sufficient contact time to remove residual chemicals, reaction by-products, and / or particles or other contaminants that have been removed by the copper oxidation solution treatment. However, it is also possible to contact an electronic component with a copper oxidizing solution and directly contact the electronic component with an etching solution, without an intermediate rinse between the two chemical treatment steps.

In the present invention, after contacting the electronic component with the etching solution, it is preferable to contact the electronic component with a deionized water rinse fluid at a temperature of about 20 ° C to about 60 ° C. This rinsing step is preferably performed after contacting the electronic component with the etching solution to remove residual chemicals, reaction by-products, and particles or other contaminants remaining on the surface of the container or electronic component. In this step, the rinse fluid preferably contains low levels of dissolved or dispersed oxygen (as described above) to minimize the risk of reoxidation of copper.

As mentioned above, it may be desirable to add surfactant to the processing liquid used in the present invention. The presence of one or more surfactants in the processing liquid (including copper oxidizing solution, etching solution or rinsing liquid) is particularly preferred when the electronic component is exposed to the gas-liquid boundary. For example, the electronic component may be exposed to the gas-liquid interface while the electronic component is immersed in the processing liquid and taken out. Electronic components may also be exposed to the gas-liquid interface while the container is filled with the processing liquid. The use of surfactants in reducing the adhesion or adsorption of particles in a number of ways is known. For example, the surfactant collects in the liquid (ie, the liquid side) at the gas-liquid interface, thereby sending out particles at the liquid side. Minimizing the amount of particles on the liquid side reduces the likelihood that the particles will come into contact with electronic components on the liquid side. In addition, surfactants provide an electrochemical barrier that prevents further particle adsorption. For example, surfactants gather on the liquid, solid or other side to help lower the overall energy, including particles and electronic components. Since the electronic components and particles are entirely surrounded by the surfactant, the overall charge of the particles / surfactant and semiconductor substrate / surfactant is approximately the charge of the surfactant. Since the particles and the semiconductor substrate have the same charge as the surfactant, they are not attracted to each other as if the opposite charge is present, thus preventing the attachment of additional particles while contained in the liquid. The choice of surfactant depends on the wet processing step. For example, the pH of the surfactant should be compatible with the pH of the chemical treatment solution (i.e., alkaline surfactants are preferably used with the copper oxidation solution, and acidic non-oxidizing surfactants are used with the etching solution). desirable).

In the most preferred embodiment of the invention, the electronic component is contacted with SC1, a copper oxide solution having a temperature of about 25 ° C. for a contact time of up to about 3 minutes. The SC1 solution preferably comprises water, ammonium hydroxide, and hydrogen peroxide in a volume ratio of about 100: 1: 1, and the surfactant in an amount of 1% by volume or less based on the total volume of copper oxidation solution. The electronic component is then preferably rinsed with deionized water for a contact time of about 5 minutes at a temperature of about 25 ° C. After being rinsed, the electronic component is preferably in contact with the hydrofluoric acid solution at a temperature of about 25 ° C. for a contact time of about 2 minutes or less. The hydrofluoric acid solution preferably comprises water, hydrofluoric acid, and hydrochloric acid in a volume ratio of about 500: 1: 1. The electronic components are rinsed again with deionized water at a temperature of about 25 ° C. for about 5 minutes and then dried with isopropanol at about 45 ° C. for about 1 minute.

In another preferred embodiment of the invention, the wet processing is carried out according to the most preferred embodiment described above, except that the copper oxidation solution comprises water and hydrogen peroxide in a volume ratio of about 100: 1 each. The copper oxidation solution also preferably contains a surfactant at the above-mentioned level and preferably no ammonium hydroxide.

According to the method of the present invention, there are several kinds of methods in which the electronic component may be wet processed. For example, in order to enhance cleaning while the electronics are in contact with the processing liquid, wet machining uses sonic energy, such as the megasonic energy range, for example from about 500 kH to about 1 MHz. Can be done. In addition, the method is described, for example, in US Pat. US Application 08 / 684,543, filed Jul. 19, 1996; 09 / 209,101, filed December 10, 1998; And 09 / 253,157 filed February 19, 1999; And US Provisional Application No. 60 / 087,758, filed June 2, 1998; And wet processing techniques disclosed in US Pat. No. 60 / 111,350, filed Dec. 8, 1998, which is incorporated by reference in its entirety.

The method of the present invention may be generally carried out in a wet processing apparatus, including, for example, a multi-tank system (eg wet bench) and a single vessel system (open or closed to the outside). For example, Chapter 1: Overview and Development of Semiconductor Wafer Contamination and Cleaning Technologies (Werner Kern) and Article in the Handbook of Semiconductor Wafer Cleaning Technology, edited by Werner Kern, published by Noyes Publication Parkridge, New Jersey, 1993. Chapter 3: Wetness in the aqueous cleaning process (Don C. Burkman, Donald Deal, Donald C. Grant, and Charlie A. Peterson), and the Ultraclean Technology Handbook, Volume 1, edited by Tadahiro Ohmi, published by MarcelDekker. Etchant cleaning (Het Etch Cleaning, Hiroyuki Horiki and Takao Nakazawa), which are incorporated by reference in their entirety.

In a preferred embodiment of the invention, the electronic component is housed in a single container system. Single vessel systems include U.S. Pat. Preference is given to using such as those disclosed in US Pat. No. 5,569,330, which is incorporated by reference in its entirety. Preferably, commercially available single vessel systems are CFM Technology's Full-Flow ™ vessels, Steeg's Poseidon, and Dainippon Screen's FL820L. Such a system is desirable because oxygen levels can be more easily controlled.

In the most preferred embodiment of the present invention, the electronic component is wet-processed in a blockable wet processing system to reduce the exposure of the electronic component to oxygen, thereby minimizing the risk of reoxidation after the surface of the electronic component is cleaned. . The breakable wet processing system also preferably receives other processing fluids in various orders. A preferred method of conveying the processing fluid to the vessel is to direct displacement of one fluid with another fluid. CFM Technology's Full-Flow ™ Wet Processing System is an example of a system capable of fluid transfer by direct displacement.

In a preferred method of the invention using a single barrier container, one discrete electronic component is placed in a processing vessel and isolated from the external environment. Before contacting the electronic component with the copper oxide solution, the electronic component may optionally be contacted with a rinsing fluid or other desired processing fluid for pretreatment of the electronic component. This contact can be achieved by pouring the fluid into the processing vessel and filling the processing vessel with fluid, so that no gas from the air or residual fluid of the previous stage remains in the vessel. The fluid may continue to be poured into the container once the container is filled with the fluid, or the flow of fluid may be stopped to soak the electronic components for a desired time. After this pretreatment step, the fluid currently contained in the vessel is removed from the vessel and the copper oxide solution is poured into the vessel to bring the electronic components into contact with the copper oxide solution. After contact with the copper oxidizing solution, the electronics can be selectively rinsed and then contacted with an etching solution such as a hydrofluoric acid containing solution. After contact with the etching solution, the electronics can be optionally rinsed or otherwise treated.

Removal of one processing fluid into another processing fluid in a single blockable vessel can be done in a number of ways. For example, the processing fluid in the processing vessel may be completely removed (ie drained) and then the next processing fluid may be added to the vessel during or after draining. In another embodiment, the processing fluid in the vessel can be replaced directly with the following preferred processing fluid, for example as disclosed in US Pat. No. 4,778,532.

After wet processing with a fluid for chemical treatment or rinsing, the electronic component is preferably dried. "Dry" preferably means that the electronic component is substantially out of the liquid droplets. By removing the droplets during drying, impurities present in the droplets when the droplets are vaporized do not remain on the surface of the semiconductor substrate. These impurities leave undesirable traces (eg water droplets) or other residue on the surface of the semiconductor substrate. However, drying may be considered to include simply removing the fluid for treatment or rinsing, for example, with the aid of a drying fluid stream or by other methods known to those skilled in the art.

Any drying method or system can be used. Preferred drying methods include, for example, evaporation, centrifugal force in a spin-rinser-dryer, chemical or steam drying, or a combination thereof.

The preferred drying method uses a drying fluid stream (hereinafter referred to as "direct displace drying") that directly replaces the last processing liquid that is contacted before the electronics are dried. Suitable methods and systems for direct replacement drying are described, for example, in US Pat. Nos. 4,778,532, 4,795,497, 4,911,761, 4,984,597, 5,571,337, and 5,569,330. Other direct replacement dryers available include Marangoni type dryers supplied by manufacturers such as Steg Dainippon, YieldUp. Most preferably, the systems and methods of US Pat. No. 4,911,761 are used for drying electronic components.

The dry fluid stream is preferably made from a partially or fully vaporized dry solution. The dry fluid stream is, for example, a mixture of superheated steam and liquid, saturated steam or a mixture of steam and traces of gas.

The dry solution selected for producing the dry fluid stream is preferably incompatible with the final processing fluid in the vessel and non-reacts with the surface of the electronic component. The drying solution also preferably has a relatively low boiling point to promote drying. For example, the dry solution is preferably selected from organic compounds having a boiling point of about 140 ° C. or less under atmospheric pressure. Examples of dry solutions that can be used include alcohols such as steam, methanol, ethanol, 1-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, or tert-amyl alcohol, acetone, acetonitrile, hexafluoroacetone, Nitromethane, acetic acid, propionic acid, ethylene glycol mono-methyl ether, difluoroethane, ethyl acetate, isopropyl acetate, 1,1,2-trichloro-1,2,2-trifluoroethane, 1,2- Dichloroethane, trichloroethane, perfluoro-2-butyltetrahydrofuran, perfluoro-1,4-dimethylcyclohexane or mixtures thereof. Preferably, the dry solution is for example C such as methanol, ethanol, 1-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, tert-amyl alcohol, pentanol, hexanol or mixtures thereof ₁ to C ₆ alcohol.

In a preferred embodiment of the present invention, the drying solution is mixed with the processing liquid present in the processing vessel immediately prior to drying and it is selected to produce a minimum-boiling minimum-boiling azeotrope with the processing liquid. Since water is the most convenient and commonly used solvent for chemical treatment or rinsing fluids, a dry solution which produces a minimum of boiling azeotropes with water is particularly preferred.

Preferably, the wet processing and drying is done in a single container without removing the electronic parts from the container in order to reduce the risk of reoxidation and contamination of the electronic parts. Suitable wet processing systems for performing wet and dry in a single container are, for example, CFM Technology's Full-Flow ™. Wet processing systems, Steig's Poseidon, and Dainippon Screen's FL820L.

After drying, the electronic component can be removed from the drying vessel and further processed in a preferred manner.

Electronic components obtained using the method of the present invention are preferably substantially free of particle contamination. "Substantially free" means that the semiconductor substrate preferably comprises 0.05 particles / cm 2 or less, more preferably 0.016 particles / cm 2 or less. The particle size of the particles remaining on the semiconductor substrate is preferably 0.3 μm or less, more preferably 0.12 μm or less, as measured by the KLA Tencor SP1 particle scanning device. Preferably, all particles larger than 0.3 μm are removed using the method of the present invention.

The method of the present invention is particularly useful for removing nonmetallic particles from the surface of electronic components. Examples of nonmetallic particles include SiO ₂ , Si ₃ N ₄ , organics, or mixtures thereof.

Example

The method of the present invention has been used to wet process semiconductor wafers having copper containing surfaces. The copper containing wafers of all examples were made of silicon and silicon oxide and completely covered with a 400 nm copper layer. After wet processing, the selected wafers were particle analyzed using a Tencor SP1 particle scanning apparatus from KLA Tencor.

Comparative Example 1-3

CFM Technology's Full-Flow ™ 8100 wet processing system was filled with copper-containing wafers. The vessel was filled with the chemical treatment solution shown in Comparative Example 1 of Table 1 for a total injection time of 120 seconds at a rate of 12 gallons / minute. The temperature of the chemical treatment solution was 30 ° C. After the vessel was full, the wafer was immersed in the chemical treatment solution for an additional 120 seconds. While the wafer was in contact with the chemical treatment solution, the wafer was exposed to megasonic energy for about 1 minute at a frequency of about 650 Hz.

The chemical treatment solution was then replaced directly with deionized water rinse solution at a temperature of 30 ° C. and containing up to about 100 ppb of oxygen. Deionized water was introduced into the processing vessel for 60 seconds at a flow rate of 24 gpm and then circulated for 60 seconds at a flow rate of 12 gpm. This cycle was repeated until the deionized water exiting the processing vessel had a resistance of 5 megohms. After reaching this resistance value, the flow of deionized water continued to circulate through the processing vessel for an additional few minutes. The total rinse time was at least 3 minutes and the wafers were exposed to megasonic energy during rinsing.

After rinsing, the wafer was dried with isopropanol vapor, a drying fluid stream. Isopropanol vapor was applied through the processing vessel for 9 minutes at a pressure of 1.5 psig.

Two or more wafer batches were processed three times in total by the method described above.

Three wafers in each wafer batch were then analyzed for particle contamination on particles ranging in size from 18 microns to 400 microns with 6 mm edge exclusion. The average results are shown in Table 2.

The processing was repeated for each of the comparative chemistry solutions shown in Table 1. In Comparative Example 3, the procedure for each Comparative Example was followed except that the vessel was filled with the chemical treatment solution at a rate of 18 gpm and the electronics were soaked for 1 minute without megasonic energy after being completely filled. Was the same as In addition, the electronic component of Comparative Example 3 was rinsed according to the procedure used in Comparative Example 1 except that the temperature of the rinse liquid was 45 ° C. and the total rinsing time was about 2 minutes.

¹ Surfactant, VALTRON ^® SP2200, Valtech Corporation

² contains oxygen up to about 100 ppb

Comparative Example 4 NH without Oxidizer ₄ Treatment with OH solution followed by HF containing solution

The Full Flow vessel used in Comparative Examples 1-3 was filled with a wafer containing copper. The vessel was filled by volume with a first chemical treatment solution having a composition of H ₂ O: NH ₄ OH: surfactant of 100: 2.2: 0.6, oxygen of about 100 ppb or less, and a temperature of 30 ° C. The first chemical treatment solution was applied into the vessel for a total injection time of 120 seconds at a rate of 12 gpm. After the vessel was full, the wafer was immersed in the first chemical treatment solution for an additional 120 seconds. The wafer was also exposed to megasonic energy at a frequency of about 650 Hz while the wafer was in contact with the first chemical treatment solution.

The first chemical treatment solution was then replaced directly with deionized water (having less than about 100 ppb oxygen), a rinse solution, according to the procedure used in Comparative Example 1. The rinse was then replaced directly with a second chemical treatment solution having a composition of H ₂ O: HF: HCl with 100: 0.2: 1 by volume, oxygen up to about 100 ppb, and a temperature of 30 ° C. The second chemical treatment solution was applied into the vessel for a total injection time of 120 seconds at a rate of 18 gpm. After the vessel was full, the wafer was immersed in the second chemical treatment solution for an additional 120 seconds (without megasonic energy).

The second chemical treatment solution was then replaced directly with deionized water, a rinse solution having less than about 100 ppb oxygen, according to the procedure used in Comparative Example 3. After rinsing, the wafers were dried according to the procedure used in Comparative Examples 1-3.

Two or more wafer batches were processed three times in total by the method described above.

Three wafers in each wafer batch were then analyzed for particle contamination for particles ranging in size from 18 microns to 400 microns with 6 mm edge exclusion. The average results are shown in Table 2.

Example 5 Treatment with Copper Oxidation Solution followed by HF Containing Solution

The procedure of Comparative Example 4 was repeated except that the first chemical treatment solution contained 100: 2.2: 1.3: 0.25 H ₂ O: H ₂ O ₂ : NH ₄ OH: surfactants by volume.

Two or more wafer batches were processed three times in total by the method described above.

Three wafers in each wafer batch were then analyzed for particle contamination for particles ranging in size from 18 microns to 400 microns with 6 mm edge exclusion. The average results are shown in Table 2.

¹ Average Light Point Defect Count

The data in Table 2 shows the average number of particles per wafer measured for three wafers. The "before" column represents the average number of particles per wafer before wet processing, the "after" column represents the average number of particles after wet processing, and the "delta" column represents particles per wafer between the "before" and "after" wet processing. The average change in is shown. A negative "delta" means that the particles were removed during the wet process. The "% removal" column represents the average percentage of particles removed relative to the number of particles present on the wafer prior to wet processing.

The data in Table 2 demonstrate that the method of the present invention is effective in reducing particle contamination during wet processing of copper containing electronic components. For example, in Example 5, 99.9% of the particles were removed by contacting the copper containing wafers with the SC1 solution, followed by contacting the wafers with a solution containing hydrofluoric acid and hydrochloric acid. These results are surprising and unpredictable when considering the comparative example. For example, a copper-containing wafer is contacted with a mixed solution of an SC1 solution (Comparative Example 1), an ammonium hydroxide solution (Comparative Example 2), a hydrofluoric acid / hydrochloric acid solution (Comparative Example 3), or an ammonium hydroxide solution and then fluorine. When contacted with a hydrofluoric acid / hydrochloric acid solution (Comparative Example 4), the% particle removal is not higher than 86%. These results are shown schematically in FIG. 1. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a bar graph showing the% particle removal in Comparative Examples 1 to 4 and 5; As can be seen in FIG. 1, the copper containing wafers processed according to the method of the present invention appeared unexpectedly superior to 4 in Comparative Example 1.

While the present invention has been described in connection with certain preferred embodiments, it will be apparent to those skilled in the art that various modifications and variations can be made to this design. The foregoing detailed description has been provided for illustrative purposes and is not intended to limit the scope of the invention.

Claims (20)

(a) contacting the surface of the electronic component with a copper oxide solution for a first contact time; And (b) then contacting the surface of the electronic component with an etching solution for a second contact time, wherein the etching solution is maintained at a pH of 5 or less and consists of an etchant and dissolved or dispersed oxygen of 5,000 ppb or less Contaminants are removed from the surface of the electronic component while the surface of the electronic component is in contact with the copper oxidation solution and the etching solution; The wet processing method of the electronic component which has the surface containing copper consisting of. The method of claim 1 wherein said copper oxidation solution consists of an oxidizing agent selected from the group consisting of hydrogen peroxide, ozone, iron cyanide and mixtures thereof. The method of claim 2, wherein the oxidant is selected from the group consisting of hydrogen peroxide, ozone, and mixtures thereof. 4. The method of claim 3, wherein the copper oxidizing solution consists of at least about 0.1 volume percent hydrogen peroxide relative to the total volume of water and copper oxidizing solution and is maintained at a pH of at least 7. The method of claim 1, wherein the copper oxidation solution consists of water, hydrogen peroxide, and ammonium hydroxide. The method of claim 5, wherein the water, hydrogen peroxide, and ammonium hydroxide are present in the copper oxidation solution in a volume ratio of H ₂ O: H ₂ O ₂ : NH ₄ OH, which is about 5: 1: 1 to about 200: 1: 1. Way. The method of claim 1, wherein the etchant is selected from the group consisting of hydrochloric acid, sulfuric acid, hydrofluoric acid, phosphoric acid, acetic acid, citric acid, tartaric acid, and mixtures thereof. The method of claim 1, wherein the etching solution is a hydrofluoric acid containing solution comprising hydrofluoric acid and deionized water in a volume ratio of H ₂ O: HF from about 5: 1 to about 1,000: 1. The method of claim 8, wherein the hydrofluoric acid containing solution is maintained at a pH of about 3 or less. The method of claim 9, wherein the hydrofluoric acid containing solution further comprises hydrochloric acid in a volume ratio of H ₂ O: HF: HCl, from about 50: 1: 1 to about 1,000: 1: 1. The method of claim 10, wherein the hydrofluoric acid containing solution comprises up to about 100 ppb of dissolved or dispersed oxygen. The method of claim 1, wherein the electronic component is rinsed with a rinse solution of deionized water after contacting the electronic component with the copper oxidation solution and before contacting the electronic component with the etching solution. The method of claim 1, wherein at least one of the copper oxidation solution or etching solution comprises a surfactant, an anticorrosive or a mixture thereof. The method of claim 1, wherein the electronic component is wet processed in one or more containers. The method of claim 1, wherein the electronic component is processed in a single container. The method of claim 15, wherein after the electronic component is in contact with the copper oxidizing solution, the copper oxidizing solution is directly replaced with a rinse solution or the etching solution. The method of claim 1, wherein the copper oxidation solution has a pH of at least about 7 or more. (a) leaving an electronic component having a surface containing at least one copper in a single container; (b) filling the vessel with a copper oxidation solution comprising an oxidant; (c) contacting the electronic component with the copper oxidizing solution for a first contact time and removing the copper oxidizing solution from the vessel; (d) filling the vessel with a hydrofluoric acid containing solution having a pH of 5 or less and comprising dissolved or dispersed oxygen of 5,000 ppb or less; And (e) contacting the electronic component with the hydrofluoric acid containing solution for a second contact time and removing the hydrofluoric acid containing solution from the vessel, wherein the surface of the electronic component is the copper oxide solution and the fluorinated Contaminants are removed from the surface of the electronic component while in contact with a hydrogen acid containing solution; The wet processing method of the electronic component which has the surface containing copper consisting of. 19. The method of claim 18, wherein the copper oxidizing solution and the hydrofluoric acid containing solution are removed from the vessel by direct displacement with another processing fluid. (a) contacting the surface of the electronic component with the copper oxidizing solution for a first contact time, wherein the copper oxidizing solution has a pH of at least about 7 or greater; And (b) then contacting the surface of the electronic component with an etching solution for a second contact time, wherein the etching solution is maintained at a pH of 5 or less and the etchant and dissolved or dispersed oxygen or other copper of 5,000 ppb or less An oxidant, wherein contaminants are removed from the surface of the electronic component while the surface of the electronic component is in contact with the copper oxidation solution and the etching solution; The wet processing method of the electronic component which has the surface containing copper consisting of.