JP2010114245A - Resist coating applicator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent non-uniformity in a film thickness of a resist film when a resist is applied to a wafer having a rugged surface, particularly non-uniformity in the film thickness in an edge part of a rugged part. <P>SOLUTION: This resist coating applicator includes: a wafer chuck 10 for directing a rugged resist coating face downward to grab a wafer W; and a resist tub 21 which is provided under the chuck 10 for containing a resist solution R, wherein the resist coating applicator holds the resist tub 21 in the water, propagates an ultrasonic wave caused by an ultrasonic oscillator 30 provided in the water, atomizes the resist solution inside the resist tub 21, and supplies it to the coating face of the wafer W. A gap g<SB>1</SB>between a leading edge face of the resist tub 21 and a rugged face of the wafer W grabbed by the wafer chuck 10 is held at a predetermined interval, an electrode 40 is formed facing the inside of the gap g<SB>1</SB>, the mist is segmented and electrified to a negative static charge, the wafer chuck 10 is grounded to electrify to a positive static charge, the mist is attracted to the rugged face of the wafer W, and the resist film with a uniform film thickness is formed on the face of the wafer W. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a resist coating apparatus for a wafer, and in particular, a resist having a uniform film thickness is formed on the surface of a wafer having a large number of irregularities such as cavities and via holes on the wafer surface (hereinafter referred to as “uneven wafer”). The present invention relates to a coating apparatus.

  As shown in FIG. 5, a conventional resist coating apparatus (spin coater) 40 for a wafer has a casing 140a whose inside can be closed, and a wafer W to which resist is applied is placed in the center of the casing 140a. A spin chuck 141 that is sucked, held, and rotated is provided. The spin chuck 141 has an upper surface that is kept horizontal, and a suction port that sucks and sucks the wafer W is provided on the upper surface, for example.

  In addition, the spin chuck 141 can be rotated at a predetermined speed (for example, 2000 rotations / minute) by a chuck driving mechanism 142 including a motor or the like.

  The chuck drive mechanism 142 is provided with an elevating drive source such as a hydraulic cylinder, and the spin chuck 141 is rotatable and vertically movable.

  Further, around the spin chuck 141, there is provided a cup 143 for receiving and collecting the resist solution scattered or dropped from the wafer W at the time of applying the resist, and the recovered resist solution is applied to the bottom of the cup 143 by a resist coating apparatus. A discharge pipe 144 that discharges to the outside and an exhaust pipe 145 that exhausts the atmosphere in the cup 143 are connected so that the inside of the cup 143 can be forcibly exhausted.

  Furthermore, a nozzle 146 that discharges the resist solution toward the wafer W is provided above the wafer W held by the spin chuck 141 so as to be movable in the horizontal and vertical directions. Further, the control unit 130 is connected to the chuck driving mechanism 142 to control the number of rotations of the wafer W and the like.

However, in such a resist coating apparatus using a conventional rotating spin chuck, a resist solution is directly sprayed from a nozzle 146 onto the surface of a wafer W having irregularities such as via holes and cavities as shown in FIG. Since the coating process is used, the resist solution is moved onto the surface of the wafer W by moving the nozzle 146 or the wafer W vertically or horizontally as shown in FIG. Even if it is applied, the resist R cannot be sufficiently applied to the cavity formed in the wafer W or the edge portion E of the via hole C compared to other portions due to variations in the particle size of the resist to be sprayed, the application direction, and the like. It was extremely difficult to form a uniform resist film thickness over the entire surface of the wafer W.
JP 2007-311469 A

  The problem to be solved by the present invention is to prevent non-uniformity of the film thickness of the resist film at the time of applying the resist to the wafer having a concavo-convex surface, particularly the non-uniformity of the film thickness at the edge of the concavo-convex part.

  In order to solve the above-described problems, the resist coating apparatus of the present invention includes a wafer chuck that holds a wafer with an uneven resist coating surface facing downward, a resist tank that contains a resist solution provided below the wafer chuck, and The resist tank is held in water, ultrasonic waves generated by an ultrasonic vibrator provided in the water are propagated in water, the resist solution in the resist tank is atomized into a mist, and the mist is removed from the wafer. An operation tank that supplies the resist coating surface, and maintains a gap between the front end surface of the resist tank and the uneven surface of the wafer held by the wafer chuck at a predetermined interval, and an electrode is provided in the gap. The mist is subdivided and charged to a negative electrostatic charge, while the wafer chuck is grounded and charged to a positive electrostatic charge, and the mist is absorbed by the uneven surface of the wafer. By, characterized in that the resist film having a uniform thickness and to form on the wafer surface. Thereby, a resist film having a substantially uniform predetermined thickness can be formed over the entire surface of the uneven wafer.

  In the resist coating apparatus of the present invention, the upper surface of the resist tank is covered with a cover having a nozzle cylinder provided so as to protrude from the center, and a gap between the tip of the nozzle cylinder and the uneven surface of the wafer is set to a predetermined value. The resist solution mist atomized from the tip of the nozzle cylinder is supplied toward the resist coating surface of the wafer while maintaining the interval.

  Furthermore, the upper surface of the resist tank is fully opened to form an opening, and a gap between the upper end of the opening and the concavo-convex surface of the wafer is maintained at a predetermined interval, and the resist mist atomized from the opening is formed. Is supplied toward the resist coating surface of the wafer.

  Furthermore, a heater is incorporated in the wafer chuck so that the temperature of the wafer held by the wafer chuck can be adjusted.

  Further, the resist coating apparatus of the present invention is provided in a wafer chuck that holds the wafer with the uneven resist coating surface facing downward, a nozzle cover provided below the wafer chuck, and a lower end portion of the nozzle cover, A spray nozzle that sprays a resist solution into the nozzle cover to form a mist, and keeps the gap between the uneven surface of the wafer and the upper end of the nozzle cover at a predetermined distance to make contact between the mist and the outside air. In addition to avoiding, changing the length of the nozzle cover changes the state of application of the resist to the wafer surface, and classifies the mist for different sizes in the height direction of the nozzle cover. And

  The resist cover may be connected to the lower end of the nozzle cover to discharge the resist solution for recovery and reuse.

  A resist film having a substantially uniform predetermined thickness can be formed over the entire wafer surface on a wafer having an uneven surface.

  Embodiments of a resist coating apparatus according to the present invention will be described below with reference to the accompanying drawings.

(First embodiment)
First, a first embodiment of the resist coating apparatus of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the resist coating apparatus 1 according to the first embodiment of the present invention includes an action tank 20 that contains an ultrasonic transducer 30 that contains water and is connected to a control system 31 at the bottom, and the action tank. A resist tank 21 that is immersed in water 20 and contains a resist solution (positive resist) used for photoresist therein, and a cover 22 that protrudes from the upper surface of the nozzle cylinder 22 a and covers the upper surface of the resist tank 21. It consists of.

Further, a wafer chuck 10 that functions as an XY table and that can be rotated and moved up and down at low speed is provided above the resist tank 21, and the resist is resisted by means such as suction on the lower surface of the wafer chuck 10. A wafer W having irregularities in the wafer surface to be coated is held so that a predetermined gap g ₁ is maintained from the tip of the nozzle cylinder 22a of the cover 22 with the irregular surface down.

Further, in this gap g _1, there is an electrode 40 that charges the mist generated by the atomization of the resist with a negative electrostatic charge and further subdivides the mist by the electrostatic atomization phenomenon to reduce the resist particle size. On the other hand, the wafer chuck 10 is grounded so as to charge the wafer W with a positive charge. The wafer chuck 10 has a built-in heater so that the temperature of the wafer W held by the wafer chuck 10 can be controlled.

  Here, the ultrasonic transducer 30 is connected to the control system 31 and configured to generate a predetermined ultrasonic vibration, and is provided at the bottom of the working tank 20 containing water so as to be easily cleaned. Yes. However, it may be provided directly in the resist tank 21 if there is no problem with the cleaning effort.

When the resist is applied on the surface of the wafer W having a concavo-convex surface using the resist coating apparatus 1 of the first embodiment of the present invention, the wafer W is attracted to the lower surface of the wafer chuck 10 with the concavo-convex surface facing downward. The gap g ₁ between the tip of the nozzle cylinder 22a provided protruding from the center of the cover 22 of the resist tank 21 and the resist coating surface of the wafer W is moved up and down at a predetermined interval by holding the wafer chuck 10 up and down. Try to keep.

  On the other hand, in order to prevent evaporation of the resist solution R in the resist tank 21 in the action tank 20 provided below the wafer chuck 10, the control system 31 is operated while maintaining the room temperature (for example, 25 ° C.), When the ultrasonic vibrator 30 is operated, the ultrasonic vibration propagates in the water in the working tank 20, and imparts ultrasonic vibration to the resist liquid R in the resist tank 21 to atomize the resist liquid R. Mist (fine particles). The fine particles m of the resist solution misted in the resist tank 21 rise while being covered with the resist tank 21 and being squeezed by the nozzle cylinder 22 a provided on the center upper surface of the cover portion 22.

  At this time, according to the knowledge of the present inventors, when the size of the fine particles m of the resist solution discharged from the nozzle cylinder 22a is 5 μm or less, it is difficult to adhere to the surface of the wafer W, and the size of the fine particles m. If the thickness is excessively large (for example, 16 μm or more), the resist-coated surface of the wafer W tends to become rough.

Therefore, in the present invention, the size of the resist fine particles m used for coating is adjusted to a predetermined size, for example, about 10 μm, by adjusting the gap g ₁ between the resist coating surface of the wafer W and the tip of the nozzle cylinder 22a. To do. Further, the thickness of the resist attached to the wafer W can be adjusted by adjusting the gap g ₁ between the wafer W and the tip of the nozzle cylinder 22a.

  Furthermore, in the first embodiment of the present invention, when the negative electrostatic charge generated by the electrode 40 is charged to the mist (fine particles) m, the mist m is further subdivided and becomes smaller. Since the positive electrostatic charge is charged, the fine particles m charged with a predetermined amount of charge are adsorbed on the surface of the wafer W, and a resist film having a uniform thickness is formed on the surface of the wafer W. become.

  At the time of resist application, the wafer chuck 10 that adsorbs the wafer W is rotated slowly (for example, 1 rotation / 1 second) or moved in the XY direction.

  Here, the wafer chuck 10 that sucks and holds the wafer W is heated to a predetermined temperature by a built-in heater and is controlled in temperature, so that the applied resist (mist) is rapidly dried to form uneven edge portions. The resist coating speed is accelerated without being swayed.

  According to the analysis of the present inventor, by using the resist coating apparatus 1 of the first embodiment of the present invention, even if the wafer W is uneven, as shown in FIG. A resist film R having a uniform film thickness (for example, about 6 μm) could be formed.

(Second embodiment)
Next, a second embodiment of the resist coating apparatus of the present invention will be described with reference to FIG.

  As shown in FIG. 2, the resist coating apparatus 1a according to the second embodiment of the present invention has a working tank 20 provided with an ultrasonic transducer 30 connected to a control system 31 as in the first embodiment. And a resist tank 21 immersed in the water of the working tank 20 and a wafer chuck 10 provided above the resist tank 20, and a surface on which the resist is applied to the lower surface of the wafer chuck 10 is uneven. A wafer W with a concave / convex surface is held downward by means such as suction.

Here, in the resist coating apparatus 1a of the second embodiment of the present invention, unlike the resist coating apparatus 1 of the first embodiment described above, the upper surface of the resist tank 21 is completely opened, and the lower surface of the wafer W and the resist are coated. The gap g ₂ with the upper end of the tank 21 is maintained at a predetermined distance, and a negative electrostatic charge is applied to the gap g ₂ by the electrode 40, so that the mist m generated in the resist tank 21 is subdivided. At the same time, a negative electrostatic charge is charged.

  In the resist coating apparatus 1a according to the second embodiment of the present invention, since the upper surface of the resist tank 21 is fully open toward the wafer W, fine particles m of the resist are rapidly formed on the wafer W surface in the image of vapor deposition. As a result, a more complete and uniform resist film is formed.

(Third embodiment)
Furthermore, a third embodiment of the resist coating apparatus of the present invention will be described with reference to FIG.

  As shown in FIG. 3, the resist coating apparatus 1b according to the third embodiment of the present invention moves a wafer W with unevenness, which is movable and rotatable in the horizontal and vertical directions with a built-in wafer temperature control heater. A wafer chuck 10 that can be adsorbed and held with the concave and convex surface facing downward, a spray nozzle 50 provided below the wafer chuck 10 for spraying a resist solution onto the wafer W, and a spray end of the spray nozzle 50 A cylindrical nozzle cover 51 that covers the nozzle cover 51, and a resist recovery conduit 52 connected to the lower end portion of the nozzle cover 51.

In particular, the resist coating apparatus 1b of the third embodiment of the present invention, a wafer chuck 10 by the lift, the predetermined distance gap g ₃ and the upper end portion of the lower surface of the wafer W and the nozzle cover 51 (e.g., 10 mm) This prevents the contact between the mist m and the outside air so that the resist mist is not affected by the outside air as much as possible. This eliminates variations in resist mist particle size.

  Further, in this third embodiment, the application state (for example, film thickness) of the resist to the surface of the wafer W can be changed by changing the length of the nozzle cover 51, and the resist mist of the nozzle cover 51 ( The fine particles) are classified into different sizes in the height direction of the nozzle cover 51 under the influence of gravity, and only the mist m having a predetermined size is applied to the surface of the wafer W. It falls without adhering to the resin, and is discharged / collected out of the system from the resist collection pipe 52, and is reused as a resist after filtration and particle size adjustment.

  The resist coating apparatus of the present invention can be used for resist coating on a wide range of wafers as well as quartz pieces.

In the first embodiment of the resist coating apparatus of the present invention, a nozzle cylinder is formed on the cover of the resist tank, and an ultrasonic vibrator is disposed on the bottom of the working tank containing water, The resist coating apparatus immersed in the water in an action tank is shown. 2 shows a resist coating apparatus according to a second embodiment of the present invention, which is a resist coating apparatus that is fully opened without providing a cover on the upper surface of the resist tank. In a third embodiment of the resist coating apparatus according to the present invention, a spray nozzle is provided directly below the wafer to which the resist is applied, and a nozzle cover having a variable length in the height direction is provided on the spray nozzle. 1 shows a resist coating apparatus that classifies mist by changing the gap between the lower surface and the tip of a nozzle cover and changes the state of application of a resist to a wafer. It is the elements on larger scale of the uneven | corrugated | grooved part (cavity or via-hole formation part) of a wafer, Comprising: The application | coating state to the wafer by the resist coating apparatus of this invention is shown. The longitudinal cross-sectional view of the spin coater (resist coating device) used for the resist application to the conventional wafer is shown. FIG. 6 is an enlarged longitudinal sectional view of a spin chuck and a spray nozzle portion of the wafer of the spin coater shown in FIG. 5. FIG. 6 shows a state in which a resist is applied to a wafer by the conventional spin coater shown in FIG.

Explanation of symbols

1, 1a, 1b Resist coating apparatus 10 Wafer chuck 20 Action tank 21 Resist tank 22 Cover 22a Nozzle cylinder 30 Ultrasonic vibrator 31 Control system 40 Electrode 50 Spray nozzle 51 Nozzle cover 52 Resist recovery line W Wafer g ₁ , g ₂ , G ₃ gap

Claims (7)

A wafer chuck for gripping the wafer with the uneven resist coating surface facing down,
A resist tank containing a resist solution provided below the wafer chuck;
The resist tank is held in water, ultrasonic waves generated by an ultrasonic vibrator provided in the water are propagated in water, the resist solution in the resist tank is atomized into a mist, and the mist is removed from the wafer. An action tank for supplying to the resist coating surface,
A gap between the front end surface of the resist tank and the uneven surface of the wafer held by the wafer chuck is maintained at a predetermined interval, and an electrode is provided in the gap to subdivide the mist and to generate a negative electrostatic charge. The wafer chuck is grounded, charged to a positive electrostatic charge, and the mist is adsorbed on the uneven surface of the wafer to form a uniform resist film on the wafer surface. A resist coating apparatus.   Cover the upper surface of the resist tank with a cover having a nozzle cylinder that protrudes from the center, and maintain the gap between the tip of the nozzle cylinder and the uneven surface of the wafer at a predetermined interval, The resist coating apparatus according to claim 1, wherein the mist of the resist solution atomized from the portion is supplied toward the resist coating surface of the wafer.   The upper surface of the resist tank is fully opened to form an opening, and a gap between the upper end of the opening and the uneven surface of the wafer is maintained at a predetermined distance, and the resist mist atomized from the opening is 2. The resist coating apparatus according to claim 1, wherein the resist coating apparatus supplies the wafer toward the resist coating surface of the wafer.   The resist coating apparatus according to claim 1, wherein a heater is built in the wafer chuck, and the temperature of the wafer held by the wafer chuck can be adjusted. A wafer chuck for gripping the wafer with the uneven resist coating surface facing down,
A nozzle cover provided below the wafer chuck;
A spray nozzle provided at the lower end of the nozzle cover and spraying a resist solution into the nozzle cover to form a mist;
The gap between the uneven surface of the wafer and the upper end of the nozzle cover is kept at a predetermined distance to avoid contact between mist and the outside air, and by changing the length of the nozzle cover, the resist can be applied to the wafer surface. A resist coating apparatus characterized by changing a coating state and classifying mist for each different size in the height direction of the nozzle cover.   The resist coating apparatus according to claim 5, wherein a resist recovery pipe line is connected to a lower end portion of the nozzle cover, the resist solution is discharged, recovered, and reused.   The resist coating apparatus according to claim 5, wherein a heater is built in the wafer chuck so that the temperature of the wafer can be adjusted.

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