JP2007273806A - Semiconductor substrate cleaning method and cleaning apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor substrate cleaning method and apparatus, capable of cleaning the semiconductor substrate that is formed with fine patterns without damaging the fine patterns. <P>SOLUTION: In a cleaning processing of the semiconductor substrate formed with the fine patterns on the surface thereof, the semiconductor substrate is held with the pattern surface thereof facing down in a cleaning processing chamber, vapor is supplied into the cleaning processing chamber to cause water drops to be condensated, and foreign substances between the fine patterns are removed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for cleaning a semiconductor substrate and a cleaning apparatus for the same, which can remove foreign matters between fine patterns without damaging the fine patterns formed on the surface of the semiconductor substrate.

  Conventionally, in a fine pattern forming process in the manufacture of a semiconductor device, after performing patterning by dry etching using a resist pattern formed by photolithography as a mask, the resist pattern is removed by a cleaning process. In the cleaning process, there is a problem in that the yield of the semiconductor device is significantly reduced unless foreign matters such as resist residues after dry etching, dry etching products and particles are removed.

  Usually, in these cleanings, chemical cleaning that removes foreign matters by chemical reaction using a chemical solution and physical cleaning that physically removes foreign matters such as applying ultrasonic waves to a cleaning solution or pure water are used. In chemical cleaning, a cleaning solution corresponding to each foreign substance to be removed is often used. For example, organic substances such as resist residues are washed using a mixed solution of sulfuric acid and hydrogen peroxide solution. For particles adhering to the substrate surface, a mixed solution of ammonia water and hydrogen peroxide solution is used. On the other hand, physical cleaning such as brushes and ultrasonic waves is often used when the particle size of foreign matter is large. In addition, when a sufficient cleaning effect cannot be obtained by either one of the cleanings, it is possible to remove foreign substances by combining chemical cleaning and physical cleaning.

  However, as the miniaturization of semiconductor devices progresses, the mechanical strength of the pattern formed on the substrate surface becomes weaker, and conventional ultrasonic cleaning methods cause pattern damage such as collapse or breakage of the fine pattern. End up. For this reason, it is difficult to remove foreign substances using physical cleaning. The damage given to the fine pattern causes the performance of the semiconductor device to deteriorate and significantly reduces the yield. As a countermeasure against this, Patent Document 1 listed below proposes a cleaning method that prevents pattern damage without deteriorating the ability to remove foreign matter by repeating two types of ultrasonic waves alternately or at regular intervals.

Further, since the pattern interval is narrowed by miniaturization, the cleaning liquid cannot enter between fine patterns due to surface tension, and a sufficient cleaning effect cannot be obtained. In order to solve this, Patent Document 2 discloses a cleaning method in which the chemical solution is supplied after the vapor is condensed between the fine patterns, thereby enhancing the effect of removing the foreign matter between the fine patterns and improving the foreign matter removing ability. Has been proposed.
JP 2002-289565 A Japanese Patent Laid-Open No. 2-177327

  However, along with further miniaturization of semiconductor devices, it is difficult not only to remove foreign substances by physical force, but also the pressure of cleaning liquid or pure water supplied to the surface of the semiconductor substrate, or centrifugation during spin cleaning. It has been confirmed that the fine pattern is also damaged by force or the like. In other words, foreign matter removal using ultrasonic waves becomes impossible, and even if the cleaning liquid can be infiltrated between the fine patterns using vapor, pressure is applied to the fine pattern simply by supplying the cleaning liquid. Will be damaged.

  Therefore, an object of the present invention is to provide a cleaning method that can effectively remove foreign matters between fine patterns without damaging the fine patterns.

  In order to solve the above-described problems, a method for cleaning a semiconductor substrate according to the present invention provides a method for cleaning a semiconductor substrate having a fine pattern formed on a surface thereof, wherein a pattern forming surface of the semiconductor substrate is formed in a processing chamber by a substrate holding mechanism. While holding downward, vapor is supplied into the processing chamber to cause condensation on the surface of the semiconductor substrate, and the foreign matter between the fine patterns is pulled away from the semiconductor substrate and dropped by its own weight to remove the foreign matter. .

  In the above cleaning method, vapor may be supplied to form droplets on the semiconductor substrate, and at the same time, a desired gas may be supplied according to the foreign matter between the fine patterns. As a result, the gas supplied to the droplets condensed on the semiconductor substrate can be dissolved, the hydrogen ion concentration of the droplets can be adjusted to a suitable value, and cleaning can be performed, and the effect of removing foreign matters from the semiconductor substrate is enhanced. be able to. Furthermore, chemical vapor generated by heating a desired cleaning liquid that can be optimally removed according to foreign matter between the fine patterns may be supplied into the processing chamber to cause condensation on the surface of the semiconductor substrate. In this case, the hydrogen ion concentration of the droplets condensed on the surface of the semiconductor substrate can be changed by controlling the concentration of the cleaning liquid to be heated, and the foreign matter removal effect can be enhanced.

  After the cleaning process using the chemical liquid vapor is performed, the liquid droplets condensed on the semiconductor substrate may be subsequently rinsed by supplying pure water vapor. Further, after the rinsing process, the drying process may be performed by supplying a drying gas such as nitrogen gas or IPA into the processing chamber.

  The semiconductor substrate cleaning apparatus according to the present invention includes a mechanism for holding the semiconductor substrate and means for supplying vapor from below to the semiconductor substrate held so that the fine pattern faces downward. In this configuration, a gas supply means for dissolving a desired chemical in the droplets condensed on the surface of the semiconductor substrate, and a pressure in the processing chamber for controlling the concentration of the gas-dissolved droplets and the hydrogen ion concentration, You may provide the mechanism which mutually controls temperature and the flow volume of the gas to supply. In addition, a mechanism for controlling the temperature of the semiconductor substrate may be provided in order to control the amount of droplets condensed on the surface of the semiconductor substrate.

  According to the present invention, foreign matters between fine patterns can be effectively removed without causing damage to the fine patterns due to physical cleaning such as ultrasonic waves. Further, according to the present invention, the concentration of droplets to be condensed can be set to an optimum concentration for removing foreign matter, and the foreign matter removing effect can be enhanced. Furthermore, an optimum cleaning process can be performed regardless of the type of foreign matter.

  Hereinafter, a semiconductor substrate cleaning method and cleaning apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  First, a foreign matter removal mechanism for cleaning using steam according to the present invention will be described with reference to FIG. Foreign matter 9 such as organic matter and particles adheres between the surface of the semiconductor substrate 4 processed with the fine pattern and between the fine patterns 6 (FIG. 1A). The vapor supplied to the semiconductor substrate 4 held so that the pattern formation surface faces downward condenses due to a temperature drop on the substrate to form droplets 10 (FIG. 1B). The droplet 10 condensed so as to surround the foreign material 9 pulls the foreign material 9 away from the semiconductor substrate 4. At the same time, the droplet 10 falls by its own weight, and the foreign matter 9 is removed from the surface of the semiconductor substrate 4 without reattaching (FIG. 1C).

  For example, when the surface of the semiconductor substrate 4 is made of silicon, a silicon oxide film, a silicon nitride film, or the like, and the foreign matter 9 is a particle containing silicon as one of the main components, the hydrogen ion concentration of droplets condensed on the substrate surface If the pH is controlled to be alkaline (hereinafter, pH), the semiconductor substrate 4 and the foreign matter 9 can be repelled using the zeta potential, and the removal effect can be enhanced. Further, when the foreign material 9 is a particle made of metal, not only the zeta potential described above but also the pH of the droplet may be controlled to be dissolved to dissolve and remove the metal. Further, when the foreign matter 9 is an organic substance such as a resist residue or a polymer, the chemical vapor is supplied to cause condensation on the substrate surface to dissolve and remove the organic foreign matter, or after oxidizing the organic foreign matter, Combining the control of pH and removal with a zeta potential can also enhance the removal of foreign matters.

  Next, a cleaning apparatus for carrying out the substrate cleaning method according to the present invention will be described with reference to the schematic view of FIG. The semiconductor substrate 4 is transferred into the cleaning processing chamber 1 with the pattern surface facing downward, and the end surface of the semiconductor substrate 4 is held by the substrate holding mechanism 3 (substrate holding means) in the upper portion of the cleaning processing chamber 1 in this state. . In the cleaning process, the temperature of the semiconductor substrate 4 is controlled by a substrate temperature control mechanism 31 (substrate temperature control means) such as a Peltier element in order to control the amount of droplets condensed on the surface. In the present embodiment, the substrate temperature processing mechanism 31 is installed above the held semiconductor substrate.

  A chemical tank 2 is installed in the lower part of the cleaning treatment chamber 1. The chemical tank 2 includes a chemical supply means 7 for supplying pure water and chemical to the chemical tank 2 from the outside of the cleaning chamber 1 and a chemical tank for heating and evaporating the supplied pure water and chemical. A temperature heater 8 and a concentration measuring device 21 for measuring the concentration of the chemical solution in the chemical solution tank 2 are provided. The cleaning processing chamber 1 is configured to be vertically separated by an atmosphere control plate 5 for controlling the supply of vapor to the semiconductor substrate 4, and nitrogen gas or mist is formed from the gas supply means 61 in a state where the supply of vapor is stopped. By supplying IPA or the like, the droplets attached to the semiconductor substrate 4 are dried.

  Further, the cleaning apparatus of the present embodiment dissolves the gas supplied to the droplets condensed on the surface of the semiconductor substrate 4 by supplying a gas such as ammonia from the gas supply means 61 during the cleaning process with steam. , The effect of removing foreign matters can be enhanced. The amount of gas dissolved in the droplets is measured by a gas flow meter 62 interposed in the gas supply means 61, and the chamber internal pressure measuring device 11 and the chamber internal temperature measuring device 12 provided in the cleaning processing chamber 1 are used in the chamber. By controlling the state (pressure and temperature) and the flow rate of the supplied gas respectively, the amount of gas dissolved in the droplets is controlled.

  Next, a method for cleaning a semiconductor substrate in the cleaning apparatus having the above configuration will be described. First, pure water is supplied from the chemical solution supply means 7 to the chemical solution tank 2. The pure water is heated by the chemical bath heating heater 8 to generate pure water vapor. The generated vapor is supplied to the semiconductor substrate 4 and is condensed on the surface of the semiconductor substrate 4 due to a temperature difference to form water droplets. At this time, the substrate temperature control mechanism 31 controls the temperature of the semiconductor substrate 4 so as to increase the amount of condensation. The water droplets formed by condensation so as to surround the foreign matter 9 are separated from the semiconductor substrate 4 and then dropped by their own weight to remove the foreign matter. At this time, the substrate holding mechanism 3 rotates the semiconductor substrate 4 at a low speed of 500 rpm or less (preferably 10 to 100 rpm) so as not to damage the pattern on the semiconductor substrate 4 in order to increase the drop efficiency of the water droplets. Or you may hold | maintain the semiconductor substrate 4 inclining to 30 degrees or less with respect to a horizontal surface.

  After performing the cleaning process for a predetermined time, the chemical tank heating heater 8 is stopped to lower the temperature of the pure water to stop the supply of steam, and the atmosphere control plate 5 causes the chemical tank 2 and the semiconductor substrate 4 to Shut off the steam supply path between. At this time, the substrate temperature control mechanism 31 increases the temperature of the semiconductor substrate 4 and decreases the amount of condensation on the semiconductor substrate 4. At the same time, by supplying nitrogen gas, misted IPA, or the like from the gas supply means 61, the reaction of oxygen to the semiconductor substrate 4 is suppressed, and water droplets remaining on the surface of the semiconductor substrate 4 while preventing the generation of watermarks and the like. Remove. At this time, in order to enhance the drying treatment effect, the inside of the separated cleaning treatment chamber 1 may be controlled under reduced pressure, and then the drying gas may be supplied. After a predetermined time, the water droplets are completely removed, and the drying process of the semiconductor substrate 4 is finished.

(Modification 1)
As described above, in the substrate cleaning method, a desired gas may be supplied from the gas supply means 61 while the vapor is supplied to the semiconductor substrate 4. Thereby, the gas supplied to the water droplets condensed on the surface of the semiconductor substrate 4 is dissolved, and the effect of removing the foreign matter 9 can be enhanced. The gas supplied at this time is preferably selected according to the material of the foreign material 9. In particular, when the foreign matter 9 is an adhering particle, it is desirable to select a gas to be supplied in accordance with each of the surface state (surface material) of the semiconductor substrate 4 as well as the foreign matter.

  For example, in the case where both the foreign matter 9 and the adhesion surface of the foreign matter 9 are mainly composed of silicon, a droplet (here, supplied) that is condensed on the surface of the semiconductor substrate 4 by supplying ammonia gas or the like from the gas supply means 61. It is preferable to control the pH of the water droplets in which the gas is dissolved to the alkali side. Thereby, the semiconductor substrate 4 and the foreign material 9 can be repelled using the zeta potential, and the effect of removing the foreign material 9 can be enhanced. As the gas supplied by the gas supply means 61, any gas can be used as long as it can make the droplets on the surface of the semiconductor substrate 4 alkaline.

  When the foreign matter 9 is a particle containing metal as a component, hydrogen chloride gas or the like is supplied from the gas supply means 61 to control the pH of the droplet condensed on the surface of the semiconductor substrate 4 to the acid side. May be. In this case, the dissolution reaction of the metal particles can be promoted, and the foreign matter 9 can be efficiently removed. As the gas supplied by the gas supply means 61, any gas can be used as long as it can make the droplets on the surface of the semiconductor substrate 4 acidic. In particular, it is preferable to use a gas that can enhance the dissolution effect of the metal component.

  In addition, you may perform a washing process combining these processes or continuously. As a result, the foreign matter 9 can be removed regardless of the type.

  Further, the pH of the droplet can be controlled by measuring the flow rate of the supply gas, measuring the chamber internal pressure and temperature, and adjusting the gas flow rate, chamber internal pressure, and chamber internal temperature. For example, when the amount of supply gas dissolved is increased, the flow rate is increased or the internal pressure or temperature is increased. Conversely, when the amount of dissolution is reduced, the flow rate of the supply gas is reduced, or the internal pressure and temperature of the chamber are reduced. In this way, by adjusting the gas flow rate, the pressure in the chamber, and the temperature in the chamber, it is possible to control the concentration and pH of the condensed droplets.

  Further, when the foreign matter 9 is an organic substance such as a resist residue, the removal effect can be enhanced by supplying ozone gas or the like from the gas supply means 61. As described above, when using a gas that is difficult to be dissolved in the water droplets, the gas is supplied from the gas supply means 61 to perform the dissolution reaction of the foreign matter 9, and then the vapor is supplied from the chemical tank 2 to remove the foreign matter. Cleaning may be performed by changing the timing at which the gas supply means 61 supplies gas, such as by removing the gas.

  As described above, when the gas is dissolved in the water droplets, pure water is supplied to the semiconductor substrate 4 and heated by supplying pure water into the chemical solution tank 2 following the cleaning process, thereby causing dew condensation. It is desirable to perform a drying process after rinsing the droplets.

(Modification 2)
By the way, in the substrate cleaning method, a chemical solution generated by supplying a desired chemical solution from the chemical solution supply means 7 into the chemical solution tank 2 and heating the chemical solution may be supplied to the semiconductor substrate 4 to cause condensation. . That is, when the foreign material 9 is an adhering particle, ammonia water is supplied to the chemical tank 2 and heated to generate ammonia vapor. By condensing ammonia water droplets on the surface of the semiconductor substrate 4, the semiconductor substrate 4 and the foreign material 9 can be repelled using the zeta potential, and the adhered particles can be effectively removed. At this time, the concentration of the chemical solution in the chemical solution tank 2 is measured by the concentration measuring device 21, and it is desirable to control the concentration and pH of the droplets condensed on the surface of the semiconductor substrate 4 based on the measurement result. Also in this modified example, as in the modified example 1, it is desirable to perform the drying process after rinsing the droplets condensed by the chemical vapor using pure water vapor.

  The embodiments described above do not limit the technical scope of the present invention, and various modifications and applications can be made within the scope of the present invention other than those already described. For example, in the above embodiment, the atmosphere control plate and the chemical solution tank are arranged below the cleaning treatment chamber. However, any arrangement may be adopted as long as the structure can supply steam from below to the fine pattern forming surface facing downward. be able to.

Schematic which shows the foreign material removal mechanism in one Embodiment of this invention. 1 is a schematic configuration diagram showing a semiconductor substrate cleaning apparatus according to an embodiment of the present invention.

Explanation of symbols

1 Cleaning treatment chamber 2 Chemical bath 3 Substrate holding mechanism (substrate holding means)
4 Semiconductor substrate 5 Atmosphere control plate 7 Chemical solution supply means 8 Heater 9 Foreign object 11 Chamber internal pressure measuring device 12 Chamber internal temperature measuring device 21 Concentration measuring device 31 Substrate temperature control mechanism (substrate temperature control means)
61 Gas supply means 62 Gas flow meter

Claims (7)

  The semiconductor substrate is held in the processing chamber with the fine pattern formation surface facing downward, and the foreign matter is removed by dewing the vapor supplied to the processing chamber and generating droplets on the surface of the semiconductor substrate. A method for cleaning a semiconductor substrate.   2. The method for cleaning a semiconductor substrate according to claim 1, wherein a foreign substance is removed by dissolving an acid-based or alkaline-based gas in droplets condensed on the semiconductor substrate.   2. The method for cleaning a semiconductor substrate according to claim 1, wherein foreign matter is removed by supplying vapor generated by heating an acidic or alkaline chemical solution to the semiconductor substrate.   4. The method for cleaning a semiconductor substrate according to claim 2, wherein a rinsing process with pure water vapor is performed after removing foreign substances. Means for holding the semiconductor substrate in the chamber;
Means for supplying vapor from below to the semiconductor substrate held in a state where the fine pattern forming surface faces downward in the holding means;
A semiconductor substrate cleaning apparatus comprising: Gas supply means for supplying a desired gas to be dissolved in droplets condensed on the surface of the semiconductor substrate;
Means for measuring the flow rate of the supply gas;
Means for measuring the pressure in the chamber;
Means for measuring the temperature in the chamber;
With
6. The amount of gas dissolved in a droplet condensed on the surface of a semiconductor substrate is controlled by mutually controlling the flow rate of the supply gas, the pressure in the chamber, and the temperature in the chamber. Semiconductor substrate cleaning equipment. 6. The semiconductor substrate cleaning apparatus according to claim 5, further comprising means for controlling a temperature of the semiconductor substrate held by the holding means.

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