JP2005235897A - Apparatus and method for substrate cleaning - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that cleaning performance cannot be ensured without causing any damage to a refined pattern. <P>SOLUTION: The substrate cleaning apparatus and the substrate cleaning method are provided with a means to oscillate an ultrasonic wave in the direction perpendicular to the flow of liquid, and a means to generate air bubbles in a cleaning liquid without transmitting the ultrasonic wave to the surface of the semiconductor substrate. Thus, the following problems can be solved: (1) the ultrasonic wave is transmitted by means of DIW (ultra pure water) or a cleaning liquid flowing on the semiconductor substrate, and the cavitation of ultrasonic wave is generated on the semiconductor substrate; (2) this action causes cracking or peeling of a refined pattern in the substrate and a pattern damage is generated; (3) when the output of ultrasonic wave is lowered to reduce an impulsive force due to cavitation, the capacity for removing particles is reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a substrate cleaning apparatus and a substrate cleaning method that can remove reaction products generated in a semiconductor device manufacturing process, particularly a dry etching process, without pattern damage.

  In the manufacturing process of a semiconductor device, it is known that various reaction products, particles, and contaminants adhere to the surface of a semiconductor substrate. For example, when an insulating film or a metal film is formed on a semiconductor substrate by a CVD (Chemical Vapor Deposition) method or a sputtering method, particulate contaminants adhere to the surface of the formed film. Further, after forming a pattern by dry etching, etching residues (resist residues), reaction products, particles, and the like adhere. As a method for removing these reaction products, particles, and contaminants, a substrate cleaning apparatus that removes particles by supplying ultrapure water with ultrasonic waves applied to the semiconductor substrate surface rotating at high speed to the semiconductor substrate surface. And a substrate cleaning method.

  Hereinafter, an example of a conventional substrate cleaning apparatus and substrate cleaning method will be described with reference to the drawings.

  FIG. 3 is a view showing a main part of a conventional substrate cleaning apparatus.

  19 is a cleaning liquid used for cleaning, 20 is an ultrasonic vibrator, 21 is a cleaning liquid discharge port, 22 is a semiconductor substrate, 23 is a chuck base for rotating the semiconductor substrate, 24 is a side nozzle for rinsing the cleaning liquid, and 25 is a cleaning liquid. The discharge nozzle 26 is a surface cup that prevents the liquid from splashing, and 27 is an ultrasonic moving nozzle incorporating the ultrasonic element 20.

  The semiconductor substrate 22 is held by the chuck base 23 and rotated between 2000 and 3000 rotations per minute. Next, DIW (ultra pure water) is discharged from the side nozzle 24 attached to the surface cup 26 onto the surface of the semiconductor substrate 22 to rinse the entire surface of the semiconductor substrate 22. Next, the rinse water discharge from the side nozzle 24 is stopped, and the cleaning liquid is discharged from the cleaning liquid discharge nozzle 25. Next, the ultrasonic moving nozzle 27 is scanned from the edge of the semiconductor substrate 22 toward the center while discharging cleaning water from the ultrasonic moving nozzle 27. The ultrasonic vibrator 20 is positioned above the cleaning liquid discharge port 21 and is set so that ultrasonic vibration generated by the ultrasonic vibrator 20 is transmitted from the cleaning liquid discharge port 21 toward the semiconductor substrate 22. The ultrasonic frequency at this time is set to 1.5 MHz, and the output is set between 10 W and 15 W. Since the ultrasonic wave propagates in the same direction as the vibration direction of the element, the ultrasonic wave propagates directly to the semiconductor substrate 22 through the cleaning liquid 19. At this time, local pressure fluctuations occur on the surface of the semiconductor substrate 22 due to cavitation in the cleaning liquid due to ultrasonic vibration propagation.

Thereafter, cleaning water is discharged from the side nozzle 24 to rinse the semiconductor substrate 22, and then the semiconductor substrate 22 is dried by high speed rotation.
JP-A-10-309548

  However, in the configuration as described above, ultrasonic waves propagate through the cleaning liquid flowing in the semiconductor substrate, and cavitation due to the ultrasonic waves occurs on the semiconductor substrate. Due to this action, cracks and peeling from the substrate occur in the fine pattern, resulting in pattern damage. Further, if the output of the ultrasonic wave is lowered in order to weaken the impact force due to cavitation, the particle removal performance is lowered. That is, there is a problem that the cleaning performance cannot be secured without causing pattern damage of the fine pattern.

  In order to solve the above problems, the substrate cleaning apparatus and the substrate cleaning method of the present invention have means for oscillating ultrasonic waves in a direction perpendicular to the flow of the liquid, and in the cleaning liquid without propagating the ultrasonic waves to the semiconductor substrate surface. It has a configuration having means for generating bubbles.

In the present invention, there is no pattern damage because cavitation does not occur on the semiconductor substrate. Also, cleaning is performed while maintaining particle removal and pattern damage-less, which is difficult with conventional ultrasonic cleaning, due to high-speed flow of cleaning liquid due to bubble generation and collapse due to cavitation in the ultrasonic vibration part of the ultrasonic moving nozzle. It is possible to improve the yield and quality in semiconductor manufacturing by having high particle removal performance without propagating ultrasonic waves to the surface of the semiconductor substrate and without causing ultrasonic damage to the fine pattern of the semiconductor device. Improvements can be realized.

  Hereinafter, an exemplary embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic view showing an ultrasonic moving nozzle used in the substrate cleaning apparatus of the present invention.

  1a is a cleaning liquid, 1b is a cleaning liquid flowing through the nozzle and cavitation is caused by an ultrasonic vibrator, 2 is a pressure adjusting valve with a flow rate adjusting mechanism of the cleaning liquid, 3 is a chemical flow meter, 4 is a main body of the cleaning nozzle, and 5 is a cleaning liquid An ultrasonic vibrator 6 for causing cavitation is shown, and 6 is a semiconductor substrate.

  About the chemical | medical solution washing | cleaning apparatus comprised as mentioned above, the operation | movement is demonstrated using FIG. 1 below.

  First, the cleaning liquid 1a is supplied to the cleaning nozzle body 4 by a pump or the like. The flow rate of the cleaning liquid 1 a can be discharged while being controlled by feeding back the value of the chemical flow meter 3 to the flow pressure regulating valve 2. An ultrasonic vibrator 5 is embedded at the tip of the cleaning nozzle, and cavitation occurs when the ultrasonic vibration is applied to the cleaning liquid 1b by the vibration of the ultrasonic vibrator 5. This phenomenon depends on the dissolved gas contained in the cleaning liquid 1b and the ultrasonic vibration frequency. Particles and residues on the surface of the semiconductor substrate 6 are removed by a high-speed flow that occurs when bubbles collapse in the cleaning liquid 1b in which cavitation has occurred.

  In the ultrasonic wave application method according to the present embodiment, since the ultrasonic vibrator is installed in the 90 degree (vertical) direction with respect to the flow of the cleaning liquid, the ultrasonic vibration propagates in the horizontal direction. As a result, pattern damage due to propagation of ultrasonic vibrations conventionally observed after ultrasonic cleaning on the semiconductor substrate does not occur.

  In the present embodiment, it is possible to change the bubble generation state generated in the cleaning nozzle by changing the ultrasonic output of the ultrasonic cleaning nozzle from 30 W to 100 W.

  In the ultrasonic cleaning nozzle of the present embodiment, the ultrasonic frequency is a low frequency of 100 kilohertz or less where cavitation is relatively likely to occur.

The cleaning liquid used is DIW (ultra pure water), functional water such as ozone water, hydrogen water, CO ₂ water (carbonated water) and cleaning chemical liquid (APM: ammonia water). It is used according to the purpose. Functional water is a cleaning ability that adjusts pH by dissolving gases such as ozone, hydrogen, and chlorine in ultrapure water to make it oxidizing / reducing, or adding a small amount of acid / alkali to this gas-dissolved water. High water.

  In this embodiment, the ultrasonic wave application direction of the ultrasonic vibrator is set so that the ultrasonic vibration propagates in the horizontal direction with respect to the flow direction of the cleaning liquid, but the ultrasonic wave propagation does not reach the wafer directly. Even if it is installed in such a range (for example, 45 degrees with respect to the flow direction of the cleaning liquid), the effect of the present invention can be achieved. Moreover, the ultrasonic wave propagation direction may be variable.

(Embodiment 2)
Hereinafter, a second embodiment of the substrate cleaning apparatus and the substrate cleaning method of the present invention will be described.

  FIG. 2 is a diagram showing a main part of the substrate cleaning method of the present invention.

  Reference numeral 11 denotes a cleaning liquid discharge nozzle, and reference numeral 12 denotes an ultrasonic moving nozzle. As described in the first embodiment, the ultrasonic vibrator is attached in a direction perpendicular to the liquid flow, and the cleaning liquid is not propagated to the wafer. Cause cavitation. 13 is a side nozzle for rinsing the cleaning liquid, 14 is a semiconductor substrate, 15 is a chuck base for rotating the semiconductor substrate, 16 is a cleaning liquid cavitation caused by the ultrasonic moving nozzle of the present invention, and 17 is a surface for preventing the liquid from scattering. It is a cup.

  About the chemical | medical solution washing | cleaning apparatus comprised as mentioned above, the operation | movement is demonstrated below using FIG.

  The semiconductor substrate 14 is rotated at a high speed (2000 to 3000 rpm) by the chuck base 15. Thereafter, rinsing is performed so that the entire surface of the semiconductor substrate 14 is wet from the side nozzle 13 on which the semiconductor substrate 14 is mounted around the surface cup. After the entire surface of the semiconductor substrate 14 is wetted by the rinsing discharged from the side nozzle 13, the rinsing by the side nozzle 13 is stopped. The rinse water from the side nozzle 13 is stopped, and the cleaning liquid is discharged from the cleaning liquid discharge nozzle 11. Thereafter, the cleaning water 16 is scanned from the edge of the semiconductor substrate 14 toward the center from the ultrasonic moving nozzle 12 of the present invention, and the nozzle is scanned. The nozzle height is swung at 10 mm in consideration of pattern damage to the semiconductor substrate 14 due to high-speed flow caused by cavitation in the ultrasonic moving nozzle 12. When the ultrasonic moving nozzle 12 is used, particles are removed by a high-speed flow caused by bubble collapse generated around the cleaning liquid nozzle and a radiant flow generated on the semiconductor substrate 14 by the rotation of the chuck base 15. Then, after rinsing with the side nozzle 13, the semiconductor substrate 14 is dried by rotating at high speed.

  In this embodiment, ultrasonic cleaning is applied to the cleaning liquid having the ability to remove organic substances and metals with functional water described in the first embodiment such as ozone water and hydrogen water as a particle removal application such as residues after dry etching. By applying vibration, radicals are generated in the cleaning liquid, so that the function of removing particles of the cleaning liquid can be further improved.

  The present invention relates to semiconductor substrate cleaning, and is useful as a cleaning method with little pattern damage. It can also be applied to the manufacture of products such as liquid crystals.

Schematic showing an ultrasonic moving nozzle used in the substrate cleaning apparatus of the present invention The figure which shows the principal part of the board | substrate cleaning apparatus of this invention The figure which shows the principal part of the conventional board | substrate cleaning apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a Cleaning liquid 1b Cleaning liquid which caused cavitation by ultrasonic vibrator 2 Pressure regulating valve with flow adjustment mechanism of cleaning liquid 3 Chemical liquid flow meter 4 Nozzle body 5 Ultrasonic vibrator 6 Semiconductor substrate 11 Cleaning liquid discharge nozzle 12 Ultrasonic moving nozzle 13 Side nozzle DESCRIPTION OF SYMBOLS 14 Semiconductor substrate 15 Chuck base 16 Cavitation-induced cleaning liquid 17 Surface cup 19 Cleaning liquid 20 Ultrasonic vibrator 21 Cleaning liquid discharge port 22 Semiconductor substrate 23 Chuck base 24 Side nozzle 25 Cleaning liquid discharge nozzle (no position movement)
26 Surface cup 27 Ultrasonic moving nozzle

Claims (5)

Means for generating ultrasonic waves in the nozzle, the ultrasonic wave vibrates the liquid in the nozzle, and the ultrasonic waves do not propagate in the liquid discharge direction, and the substrate cleaning apparatus having a nozzle . The substrate cleaning apparatus according to claim 1, wherein the propagation direction of the ultrasonic wave is substantially perpendicular to the nozzle discharge direction. The substrate cleaning apparatus according to claim 1, wherein an ultrasonic wave propagation direction is variable with respect to a nozzle discharge direction. 4. The substrate cleaning apparatus according to claim 1, wherein the position of the cleaning nozzle is variable with respect to the substrate to be cleaned. Means for generating ultrasonic waves in the nozzle, and the ultrasonic waves vibrate the liquid in the nozzle, and the ultrasonic waves are ultrasonically vibrated using a nozzle characterized in that the ultrasonic waves do not propagate in the liquid discharge direction. A substrate cleaning method for cleaning a substrate to be cleaned by using a high-speed flow due to pressure fluctuation of bubble collapse for a liquid containing bubbles due to a generated cavitation effect.

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