JP2009032710A - Substrate processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively remove particles adhered to a substrate while avoiding damage to a structure formed on the substrate surface. <P>SOLUTION: A substrate processing apparatus 1 is configured to remove particles adhered to a semiconductor wafer W with minute air bubbles by imparting ultrasonic oscillation to a cooled processing liquid with a dissolved inert gas while immersing the semiconductor wafer W into the processing liquid. In the substrate processing apparatus 1, an inert gas is dissolved into the processing liquid cooled by a chiller 126 in a dissolution part 128 and the processing liquid 104, into which an inert gas is dissolved by the dissolution part 128, is stored in a processing tank 102. An ultrasonic transducer 156 imparts ultrasonic oscillation to the processing liquid 104 via the bottom part of a propagation tank 152, propagation water 154, and the bottom part of the processing tank 102. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a substrate processing apparatus that removes particles adhering to a substrate such as a semiconductor wafer or a glass substrate for a liquid crystal display device using a processing solution such as ammonia water or pure water.

  The removal of the particles adhering to the semiconductor wafer is performed by immersing the semiconductor wafer in a treatment liquid such as ammonia water (SC-1) in which an alkaline aqueous solution such as ammonia water, hydrogen peroxide water and pure water are mixed, In general, it is performed by releasing particles from the surface of the semiconductor wafer by utilizing the action. In this case, the treatment liquid is often heated to room temperature or higher. In addition, in removing particles adhering to the surface of a semiconductor wafer, ultrasonic waves in the megahertz band are generated, ultrasonic vibrations are propagated to the semiconductor wafer through the processing liquid, and the semiconductor is utilized by utilizing physical force generated by the ultrasonic vibrations. Particles are also released from the surface of the wafer.

  However, if particles attached to the semiconductor wafer are removed using physical force generated by ultrasonic vibration, the structure (for example, cylinder) formed on the surface of the semiconductor wafer is damaged by the physical force. There is.

  Therefore, it is also considered to prevent damage to the structure formed on the surface of the semiconductor wafer by dissolving the inert gas in the treatment liquid and causing the inert gas dissolved in the treatment liquid to play the role of a cushion. Has been.

  Patent Document 1 and Patent Document 2 are prior art documents related to the present invention, and disclose a technique for performing megasonic cleaning after dissolving an inert gas in a treatment liquid.

JP 2004-22572 A JP 2004-79990 A

  However, when the structure of a semiconductor device is miniaturized and a structure having a high aspect ratio is formed on the surface of a semiconductor wafer, the above-described damage prevention measure that simply uses a processing solution in which an inert gas is dissolved is not sufficient. A sufficient effect may not be obtained. In addition, when the processing considering only damage prevention measures is performed, there is a problem that particles cannot be effectively removed.

  The present invention was made to solve this problem, and a substrate that effectively removes particles adhering to the substrate while avoiding damaging structures formed on the surface of the substrate such as a semiconductor wafer. An object is to provide a processing apparatus.

  In order to solve the above problems, the invention of claim 1 is a substrate processing apparatus, wherein a processing tank for storing a processing liquid, a holding means for holding a substrate in the processing liquid stored in the processing tank, and the processing A treatment liquid supply means for supplying a treatment liquid to the tank; a pipe connected to the treatment liquid supply means for supplying the treatment liquid to the treatment liquid supply means; and a cooling means provided in the pipe for cooling the treatment liquid. A dissolving means for dissolving an inert gas in a treatment liquid cooled by the cooling means, provided in a pipe downstream from the position where the cooling means is provided; and a treatment liquid stored in the treatment tank. And an ultrasonic wave generating means for generating an ultrasonic vibration for applying the ultrasonic vibration.

  A second aspect of the present invention is the substrate processing apparatus according to the first aspect, wherein the substrate processing apparatus is dissolved in a thermometer that measures the temperature of the processing liquid stored in the processing tank, and the processing liquid stored in the processing tank. A concentration meter that measures the concentration of the inert gas, and when the liquid temperature measured by the thermometer is 10 ° C. or less and the concentration measured by the concentration meter is a predetermined concentration or more, the generation of the ultrasonic wave And a control unit for starting generation of ultrasonic waves by the means.

  According to a third aspect of the present invention, in the substrate processing apparatus according to the second aspect of the present invention, the substrate processing apparatus further includes an adjusting unit that adjusts an amount of an inert gas dissolved in the processing liquid by the dissolving unit, and the control unit generates the ultrasonic wave After operating the means, the adjusting means is controlled to increase the amount of inert gas dissolved in the processing liquid by the dissolving means.

  According to a fourth aspect of the present invention, in the substrate processing apparatus according to the third aspect, the control unit controls the adjusting means based on the concentration measured by the densitometer and dissolves it in the processing liquid by the dissolving means. The amount of the inert gas is increased.

  According to the present invention, since the inert gas is dissolved in the processing liquid cooled by the cooling means, a large amount of microbubbles can be generated in the processing liquid, and the structure formed on the surface of the substrate. The particles adhering to the substrate can be effectively removed without damaging the substrate.

  According to the invention of claim 2, since the amount of the inert gas dissolved in the processing liquid is increased and the ultrasonic vibration is applied after the density of the processing liquid is increased, the particles adhering to the substrate are removed. It can be removed more effectively.

  According to the invention of claim 3, since the amount of the inert gas dissolved in the treatment liquid by the dissolving means is increased after the ultrasonic wave generating means is operated, the treatment decreased by application of ultrasonic vibration to the treatment liquid. The concentration of the inert gas in the liquid can be recovered.

<1. Configuration of substrate processing apparatus>
FIG. 1 is a schematic view of a substrate processing apparatus 1 according to a preferred embodiment of the present invention. The substrate processing apparatus 1 removes particles adhering to the semiconductor wafer W by applying ultrasonic vibration to the processing liquid while the semiconductor wafer W is immersed in a processing liquid that has been cooled and dissolved with an inert gas. To do. The substrate processing apparatus 1 is a batch type cleaning apparatus that processes a plurality of semiconductor wafers W simultaneously. In addition to the semiconductor wafer W, the substrate processing apparatus 1 can process various substrates such as a glass substrate for a liquid crystal display device, a glass substrate for a plasma display panel, a glass substrate for a magnetic disk or an optical disk, or a ceramic substrate. .

  As shown in FIG. 1, the substrate processing apparatus 1 mainly includes a processing tank 102, a propagation tank 152, an ultrasonic transducer 156, a lifter 158, and a control unit 160.

The processing tank 102 whose cross section is shown in FIG. 1 stores the processing liquid 104 therein, and can be immersed in the processing liquid 104 storing a plurality of semiconductor wafers W processed simultaneously in the substrate processing apparatus 1. It has a container shape. As the treatment liquid 104, pure water or a mixed liquid obtained by mixing pure water and other solutions, for example, pure water, hydrogen peroxide water (H ₂ O ₂ ), and ammonia water (NH ₃ ) in a volume ratio. A mixed liquid (SC-1) mixed at a ratio of 100: 2: 1 can be employed.

  A pair of nozzles 106 for discharging the supplied processing liquid toward the inside of the processing tank 102 is provided in the vicinity of the inner bottom surface of the processing tank 102. A plurality of discharge holes for discharging the processing liquid 104 into the processing tank 102 are formed in the pair of nozzles 106 along the arrangement direction of the semiconductor wafers W, respectively. In the vicinity of the upper end of the outer surface of the processing tank 102, an outer tank 108 for collecting the processing liquid overflowing from the upper part of the processing tank 102 is provided.

  In addition, a thermometer 110 that measures the temperature of the treatment liquid 104 and a concentration meter 112 that measures the concentration of an inert gas dissolved in the treatment liquid 104 are provided inside the treatment tank 102. The measurement results of 110 and the densitometer 112 are acquired by the control unit 160.

  The substrate processing apparatus 1 includes a pipe 122 that constitutes a circulation path of the processing liquid that leaves the processing tank 102 and returns to the processing tank 102. The pipe 122 has one end connected to the nozzle 106 and the other end connected to the bottom of the outer tub 108, and a pump 124 for feeding the processing liquid in order from upstream to downstream, and a chiller 126 for cooling the processing liquid. And a dissolving unit 128 for dissolving the inert gas in the processing liquid, and a filter 130 for filtering floating substances in the processing liquid. The operations of the pump 124 and the chiller 126 are controlled by the control unit 160. In the substrate processing apparatus 1, the processing liquid 104 is circulated through the pipe 122 by feeding the processing liquid with the pump 124, and the processing liquid collected in the outer tank 108 is re-supplied to the processing tank 102 through the nozzle 106.

One end of a pipe 142 serving as an inert gas supply path is connected to the dissolving portion 128. The pipe 142 is provided with a valve 144 for opening and closing the pipe 142 and a flow rate controller 146 for controlling the flow rate of the inert gas, and an inert gas supply source 148 is connected to the other end of the pipe 142. Yes. For example, nitrogen gas (N ₂ ) can be employed as the inert gas. The operations of the valve 144 and the flow rate controller 146 are controlled by the control unit 160.

  FIG. 2 is a schematic diagram of the dissolving portion 128. As shown in FIG. 2, the dissolving unit 128 mainly includes a main body 172, a processing liquid inlet 180, a processing liquid outlet 186, and inert gas inlets 182 and 184. The dissolving unit 128 dissolves the inert gas introduced from the inert gas inlets 182 and 184 in the processing liquid 104 taken from the processing liquid inlet 180 and sends it out from the processing liquid outlet 186.

  2 has a structure in which a liquid supply pipe 176 and a large number of hollow fiber separation membranes 178 are built in a cylindrical container 174 closed at both ends.

  The liquid supply pipe 176 is disposed on the cylindrical axis of the cylindrical container 174 and is connected to a processing liquid inlet 180 provided on the first end face of the cylindrical container 174. The liquid supply pipe 176 guides the processing liquid taken from the processing liquid inlet 180 into the cylindrical container 174 and discharges the processing liquid in the radial direction D1 of the cylindrical container 174 inside the cylindrical container 174. Thereby, the inside of the cylindrical container 174 is filled with the processing liquid.

  The thin cylindrical hollow fiber separation membrane 178 is coaxially disposed around the liquid supply pipe 176, and the inert gas inlet 182 provided on the first end surface of the cylindrical container 174 or the first of the cylindrical container 174 is provided. 2 is connected to an inert gas inlet 184 provided on the end face of the second end. The hollow fiber separation membrane 178 is made of a material that transmits an inert gas but does not transmit the treatment liquid 104. As a result, when the inert gas is pressurized and supplied to the inert gas inlets 182 and 184 while the hollow fiber separation membrane 178 is immersed in the treatment liquid, the inside of the treatment liquid passes through the hollow fiber separation membrane 178. An inert gas is supplied to the solution, and the inert gas is dissolved in the treatment liquid. Here, the amount of the inert gas dissolved in the treatment liquid in the dissolving unit 128 is adjusted by the flow rate controller 146.

  Referring back to FIG. 1, a propagation tank 152 that stores propagation water 154 that propagates ultrasonic vibrations to the treatment tank 102 is disposed below the treatment tank 102, and the bottom of the treatment tank 102 is the propagation water 154. Soaked in Further, an ultrasonic transducer 156 that generates megahertz ultrasonic vibration is attached to the outer bottom of the propagation tank 152. The operation of the ultrasonic transducer 156 is controlled by the control unit 160. The ultrasonic vibration generated by the ultrasonic vibrator 156 is applied to the treatment liquid 104 via the bottom of the propagation tank 152, the propagation water 154, and the bottom of the treatment tank 102.

  The lifter 158 holds a plurality of semiconductor wafers W (for example, 50 wafers) that are simultaneously processed in the substrate processing apparatus 1 at a predetermined interval, and a processing position and processing in the processing tank 102 by a driving mechanism (not shown). It moves up and down between the upper position of the tank. The operation of the lifter 158 by the drive mechanism is controlled by the control unit 160.

  The lifter 158 immerses the semiconductor wafer W received from the previous process in the processing liquid 104 in the processing bath 102, holds the semiconductor wafer W in the processing liquid 104, and is immersed in the processing liquid 104. Raise W and hand it over to the next process.

  The control unit 160 is configured to include an embedded computer, and comprehensively controls each component of the substrate processing apparatus 1 as described above.

<2. Operation of substrate processing apparatus>
FIG. 3 is a flowchart for explaining the operation of the substrate processing apparatus 1 when particles adhering to the semiconductor wafer W are removed.

  In processing the semiconductor wafer W, first, the operation of the pump 124 is started under the control of the control unit 160, and the circulation of the processing liquid is started (step S101).

  Next, under the control of the control unit 160, the operation of the chiller 126 is started, the cooling of the processing liquid is started (step S102), the valve 144 is opened, and the inert gas is supplied to the dissolving unit 128. Is started (step S103). Accordingly, in the substrate processing apparatus 1, the inert gas is dissolved in the processing liquid cooled by the chiller 126 in the dissolving unit 128, and the processing liquid 104 in which the inert gas is dissolved by the dissolving unit 128 is added to the pipe 122. Is supplied from the pair of nozzles 106 into the processing tank 102.

  Subsequently, the control unit 160 acquires the liquid temperature measured by the thermometer 110 and the concentration measured by the concentration meter 112 (step S104), and the liquid temperature is equal to or lower than a predetermined value and the concentration is equal to or higher than a predetermined value (for example, a non-standard value). When the concentration of the active gas reaches a value close to the saturation concentration (“YES” in step S105), the ultrasonic vibrator 156 is operated to start applying ultrasonic vibration to the processing liquid 104 (step S106). Due to this ultrasonic vibration, micro bubbles (cavities) that contribute to the removal of particles adhering to the semiconductor wafer W are generated in the processing liquid 104.

  On the other hand, if the temperature is not lower than the predetermined value or the concentration is not higher than the predetermined value ("NO" in step S105), the control unit 160 returns to step S104 and acquires the liquid temperature and concentration again. To do. Thereby, in the substrate processing apparatus 1, the application of ultrasonic vibration to the processing liquid 104 is not started until the liquid temperature is equal to or lower than the predetermined value and the concentration is equal to or higher than the predetermined value.

  The reason for controlling the liquid temperature and concentration in this way is as follows. 4A and 4B are diagrams showing the state of microbubbles in the processing liquid. FIG. 4A shows the prior art and FIG. 4B shows the technique of the present invention.

  In the conventional technique shown in FIG. 4A, an inert gas is dissolved in the processing liquid at room temperature. When ultrasonic vibration is applied to the processing liquid in the processing tank, microbubbles are generated. The microbubbles are changed in size by application of further ultrasonic vibration, and finally the microbubbles are ruptured, and particles on the surface of the semiconductor wafer W are removed by the impact of the rupture of the microbubbles.

  However, since the number of microbubbles generated in the processing liquid is small, particle removal by impact of bursting of microbubbles is not sufficient. In addition, since the size of the microbubbles is large and the number thereof is small, the ultrasonic vibration that has passed through the microbubbles will damage the structure formed on the surface of the semiconductor wafer.

  On the other hand, in the technique of the present invention, when the temperature of the processing liquid is first set to 10 ° C. or less by the chiller 126, the density of the processing liquid 104 increases. Therefore, the dissolved amount of the inert gas in the treatment liquid is increased as compared with the conventional technique. When ultrasonic vibration from the ultrasonic vibrator 156 is applied to the treatment liquid in which the dissolved amount of the inert gas is increased, many micro bubbles (cavities) in the treatment liquid are generated. Since the density of the processing liquid is increased by cooling the processing liquid at this time, the size of the microbubbles is smaller than that at normal temperature and the density of the microbubbles is improved, so that a large amount of microbubbles are generated ( FIG. 4 (b)).

  Furthermore, if ultrasonic vibration is continuously applied to the microbubbles, the microbubbles are changed into large and small by the ultrasonic vibration, and finally a large amount of microbubbles are ruptured. Compared with the technique, particles on the surface attached to the semiconductor wafer W can be effectively removed. At this time, since a large amount of microbubbles are generated in the processing liquid, the ultrasonic vibration from the ultrasonic transducer 156 is relaxed by the large amount of microbubbles (FIG. 4B), and the semiconductor wafer. It is possible to prevent damage to the structure formed on the surface.

  Subsequently, the control unit 160 controls the flow rate controller 146 based on the detection result of the inert gas concentration by the densitometer 112 to increase the amount of the inert gas supplied to the dissolving unit 128, thereby In 128, the amount of the inert gas dissolved is increased (step S107). As described above, since the amount of the inert gas dissolved in the processing liquid 104 is increased after the ultrasonic vibrator 156 is operated, the concentration of the inert gas lowered by the application of the ultrasonic vibration is reliably recovered. it can.

  Thereafter, under the control of the controller 160, the lifter 158 immerses the semiconductor wafer W in the processing liquid 104, and holds the semiconductor wafer W in the processing liquid 104 for a predetermined time (step S108). Thereby, the particles adhering to the semiconductor wafer W are removed along with the bursting of the microbubbles.

<3 Treatment liquid temperature>
It is desirable that the temperature of the processing liquid 104 is equal to or higher than the freezing point of the processing liquid 104 and the density of the processing liquid 104 is as high as possible. Accordingly, the desired liquid temperature of the processing liquid 104 varies depending on the type of the processing liquid 104. However, in the case of the processing liquid 104 containing pure water as a main component, the temperature is set to 0 ° C. or higher and 20 ° C. or lower where the density increases to some extent. Is desirable, and it is more desirable to set it as 0 degreeC or more and 10 degrees C or less. This is because the density of the treatment liquid 104 can be increased within this range, as shown in FIG. FIG. 5 is a graph showing the dependence of the density of pure water on the liquid temperature.

It is a schematic diagram of the substrate processing apparatus which concerns on embodiment. It is a schematic diagram of the melt | dissolution part. It is a flowchart explaining operation | movement of the substrate processing apparatus of embodiment. It is a figure which shows the state of the microbubble in a process liquid. It is a figure which shows the dependence with respect to the liquid temperature of the density of a pure water.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate processing apparatus 102 Processing tank 104 Processing liquid 126 Chiller 128 Melting | dissolving part 156 Ultrasonic vibrator 158 Lifter 160 Control part

Claims (4)

A treatment tank for storing the treatment liquid;
Holding means for holding the substrate in the processing liquid stored in the processing tank;
Treatment liquid supply means for supplying a treatment liquid to the treatment tank;
A pipe connected to the processing liquid supply means and supplying the processing liquid to the processing liquid supply means;
A cooling means provided in the pipe for cooling the treatment liquid;
Dissolving means for dissolving an inert gas in a treatment liquid provided in a downstream pipe from a position where the cooling means is provided, and cooled by the cooling means;
Ultrasonic generation means for generating ultrasonic vibrations for applying ultrasonic vibrations to the processing liquid stored in the processing tank;
A substrate processing apparatus comprising: A thermometer for measuring the temperature of the processing liquid stored in the processing tank;
A concentration meter that measures the concentration of the inert gas dissolved in the treatment liquid stored in the treatment tank;
When the liquid temperature measured by the thermometer is 10 ° C. or lower and the concentration measured by the densitometer is equal to or higher than a predetermined concentration, a control unit that starts generation of ultrasonic waves of the ultrasonic wave generation unit;
The substrate processing apparatus according to claim 1, further comprising: An adjusting means for adjusting the amount of inert gas dissolved in the treatment liquid by the dissolving means;
3. The control unit according to claim 2, wherein, after operating the ultrasonic wave generation unit, the control unit controls the adjustment unit to increase the amount of an inert gas dissolved in the processing liquid by the dissolution unit. Substrate processing equipment.   The said control part controls the said adjustment means based on the density | concentration measured by the densitometer, and increases the quantity of the inert gas dissolved in a process liquid by the said dissolution means. Substrate processing equipment.

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