TW201805071A - Coating film formation device, coating film formation method, and storage medium - Google Patents

Abstract

The invention provides a technique which, when forming a coating film on a substrate, suppresses the introduction of bubbles into the coating film. Processing is performed so as to implement a first step in which a coating liquid is supplied to a substrate to form a localized liquid pool A1 at the central part of the substrate, a second step in which a diluting liquid is supplied only to the periphery of the liquid pool A1 to form a mixed liquid A2, and a third step in which the substrate is rotated and the resulting centrifugal force causes the mixed liquid A2 to spread towards the periphery of the substrate thereby covering the periphery of the substrate with the mixed liquid A2, and causes the liquid pool to spread towards the periphery of the substrate that is covered by the mixed liquid A2, thereby forming the coating film.

Description

Coating film forming apparatus, coating film forming method, and recording medium

The present invention relates to the technical field of supplying a coating liquid to a substrate to form a coating film.

In the semiconductor lithography technology, various coating liquids are supplied to the surface of a semiconductor wafer (hereinafter referred to as a "wafer") as a substrate to form a coating film. Generally, the formation of this coating film is performed by the centrifugal force generated by the rotation of the wafer to extend the coating liquid supplied to the center portion of the wafer to the peripheral portion of the wafer, that is, by so-called spin coating. Examples of the coating liquid include photoresist. This photoresist may be used, for example, in order to obtain a larger film thickness.

However, it has been found that if such a high-resistance photoresist is applied by spin coating, bubbles may be mixed in the peripheral portion of the formed photoresist film. It is presumed that when the photoresist is extended to the periphery of the wafer, the solvent contained in the photoresist gradually dries and the photoresist viscosity becomes higher, resulting in a branch called fingering. The diffusion phenomenon, and when the photoresist diffuses like this, the air on the wafer surface becomes entangled and becomes a bubble generator. In addition, when a photoresist is applied, a recess may be formed on the wafer surface. In this case, as described above, the photoresist whose viscosity is increased during stretching cannot sufficiently enter the recessed portion. As a result, the air in the recessed portion may remain in the photoresist film and become a bubble.

Patent Document 1 describes that after a coating liquid is supplied to the center portion of a wafer, a dilution liquid is supplied to the center portion of the wafer to form a mixed liquid. After the following state is formed, the coating liquid is present on the peripheral portion of the wafer. After the mixed solution with a high concentration is in a state where the mixed solution with a low concentration of the coating liquid is present at the center of the wafer, the concentration of the coating liquid on the wafer surface is averaged by the rotation of the wafer to form Coating film. However, Patent Document 1 here refers to a liquid tank that supplies a dilution liquid to cover the entire coating liquid. According to this method, it is generally considered that since the viscosity of the coating liquid is excessively reduced, it is difficult to control the film thickness of the coating film, and in particular, it is difficult to make the film thickness of the coating film large. Patent Document 2 describes that when a photoresist film is formed on a quadrangular substrate, when a photoresist is applied, a solvent mist or a solvent vapor is supplied to the substrate to adjust the solvent concentration of the air flow on the corner of the substrate. . The supply of the solvent is performed only on the corners of the quadrangular substrate, and the problem of the above-mentioned air bubbles generated on the peripheral edge of the substrate when the substrate is coated with photoresist by spin coating is not considered, which cannot be solved. Disclosure of the issue. [Known Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2010-225871 [Patent Document 2] Japanese Patent Laid-Open No. 2005-235950

[Problems to be Solved by the Invention] The present invention has been developed in order to solve such problems, and its subject is to provide a technology that can prevent bubbles from being mixed into the coating film when forming a coating film on the substrate. [Technical means to solve problems]

The coating film forming device of the present invention includes: a substrate holding portion that holds the substrate horizontally; a rotating mechanism that rotates the substrate held by the substrate holding portion; a coating liquid supply nozzle for supplying a central portion of the substrate to the substrate; A coating liquid for forming a coating film on the surface of the substrate; a dilution liquid supply nozzle for supplying a dilution liquid for reducing the viscosity of the coating liquid to the substrate to form a mixed liquid obtained by diluting the coating liquid; Control signals of the first step, the second step, and the third step; the first step is to supply the coating liquid to the substrate to form a liquid pool locally at the center portion of the substrate; then, the second The step is limited to supplying a diluent to the peripheral portion of the liquid pool to form a mixed liquid. Next, in the third step, the substrate is rotated to extend the mixed liquid to the peripheral portion of the substrate by centrifugal force, and The peripheral edge portion of the substrate is covered with the mixed liquid, and the liquid pool is extended to the peripheral edge portion of the substrate covered with the mixed liquid to form the coating film.

The coating film forming method of the present invention includes the following steps: a step of holding the substrate horizontally by a substrate holding portion; and then, supplying a coating liquid for forming a coating film on the surface of the substrate through a coating liquid supply nozzle to the substrate, A step of forming a liquid pool locally at the central portion of the substrate; thereafter, by using a diluent supply nozzle, only the peripheral portion of the liquid pool is supplied with a dilution liquid for reducing the viscosity of the coating liquid to form a dilution of the coating liquid A step of forming the mixed liquid; and then, rotating the substrate by a rotating mechanism that rotates the substrate through the substrate holding portion to extend the mixed liquid to a peripheral portion of the substrate by centrifugal force, and use the mixed liquid The peripheral portion of the substrate is covered, and the liquid pool is extended to the peripheral portion of the substrate covered with the mixed solution to form the coating film.

The recording medium of the present invention stores a computer program for a coating film forming device for forming a coating film on a substrate; the computer program is prepared with a group of steps for implementing the coating film forming method described above. [Effect of Invention]

According to the present invention, after the liquid pool of the coating liquid is formed at the central portion of the substrate, the dilution liquid is limited to the peripheral portion of the liquid pool to form a mixed liquid; thereafter, the peripheral edge of the substrate is covered with the mixed liquid by the centrifugal force of the substrate rotation. Further, the "peripheral portion of the substrate to which the mixed liquid is supplied" is covered with the coating liquid to form a coating film. Since it is mixed with the mixed liquid supplied to the peripheral edge portion of the substrate first, and the coating liquid is diffused to the peripheral edge portion of the substrate, the drying of the coating liquid can be suppressed; as a result, the covering property of the coating liquid on the substrate can be suppressed. Since it reduces, it can suppress that a bubble mixes in a coating film.

A photoresist film forming apparatus 1 according to an embodiment of the coating film forming apparatus of the present invention will be described with reference to a perspective view of FIG. 1 and a vertical side view of FIG. 2. This photoresist film forming apparatus 1 supplies a photoresist as a coating liquid to the surface of a wafer W as a substrate, and forms a photoresist film as a coating film. 11 in the figure is a rotary chuck serving as a substrate holding portion, which holds the center portion of the back surface of the wafer W and holds the wafer W horizontally. The 12-series rotation mechanism in the figure is connected to the rotation chuck 11 via a shaft portion 13. The rotation chuck 11 is rotated by the rotation mechanism 12 so that the wafer W held by the rotation chuck 11 is rotated around its central axis.

14 in FIG. 2 is a horizontal circular plate, which is disposed below the rotary chuck 11 as if it surrounds the shaft portion 13. Reference numeral 15 in the figure is a lifting thimble provided through the circular plate 14 and is provided with 3 pins to support the wafer W (only 2 pins are shown in FIG. 2). These lifting and ejecting pins 15 are configured to be lifted and lowered freely by a lifting and lowering mechanism 16, and the wafer W is transferred between the conveying mechanism outside the photoresist film forming apparatus 1 and the rotary chuck 11 by lifting and lowering.

The 2 series cup body in the figure is arranged to rotate around the chuck 11. The function of the cup 2 is to receive the liquid discharged from the rotating wafer W by flying or splashing, and discharge the liquid to the outside of the photoresist film forming apparatus 1. The cup body 2 includes a mountain-shaped guide 21 provided in a ring shape and a mountain-shaped cross-section around the circular plate 14. A ring extending downward from the outer peripheral edge of the mountain-shaped guide 21 is provided.状 的 Vertical wall 22. The mountain-shaped guide portion 21 guides the liquid splashed from the wafer W under the outside of the wafer W.

Furthermore, a cylindrical portion 23 perpendicular to the outer side of the mountain-shaped guide portion 21 and an intermediate guide portion 24 extending obliquely upward and upward from the upper edge of the cylindrical portion 23 are provided. The intermediate guide portion 24 is provided with a plurality of opening portions 25 in the circumferential direction. Furthermore, a cylindrical portion 26 is provided to extend upward from the peripheral edge of the base end side of the intermediate guide portion 24, and an inclined wall protruding upward from the upper edge of the cylindrical portion 26 is provided. 27.

In the lower side of the cylindrical portion 23, a ring-shaped liquid receiving portion 31 having a concave cross section is formed below the mountain-shaped guide portion 21 and the vertical wall 22. Here, the liquid receiving portion 31 is connected to the liquid discharge path 32 on the outer peripheral side. The liquid scattered by the rotation of the wafer W is received by the inclined wall 27, the intermediate guide portion 24, and the cylindrical portion 23 and introduced.排 液 路 32。 Liquid drainage path 32. An exhaust pipe 33 is provided in the liquid receiving portion 31 on the inner peripheral side than the liquid discharge path 32 so as to extend from below; during the processing of the wafer W, the gas inside the cup body 2 is discharged.

41 in the figure is a vertical cylindrical photoresist supply nozzle, which releases photoresist vertically downward. The 42-series photoresist supply unit in FIG. 2. The photoresist supply unit 42 includes, for example, a liquid tank storing a photoresist, a pump, a filter, and a valve. The photoresist can be supplied from the liquid tank to the photoresist supply nozzle 41 at a predetermined flow rate. The viscosity of the photoresist supplied from the photoresist supply unit 42 to the photoresist supply nozzle 41 and released to the wafer W is, for example, 500 cP to 5000 cP.

43 in FIG. 1 is an arm body that supports the photoresist supply nozzle 41 with its front end side, and a moving mechanism 44 is connected to the base end side of the arm body 43. The moving mechanism 44 is configured to lift and lower the arm body 43 and move freely in the horizontal direction along the guide rail 45. Reference numeral 46 in the figure is a standby portion that makes the photoresist supply nozzle 41 stand by when the wafer W is not being processed.

The reference numeral 51 in the figure is a vertical cylindrical thinner supply nozzle, which releases the thinner vertically downward as a solvent for the photoresist. The 52 series thinner supply unit in FIG. 2. The diluent supply unit 52 includes, for example, a liquid tank storing a diluent, a pump, a filter, a valve, and the like, and can supply the diluent to the diluent supply nozzle 51 at a predetermined flow rate from the liquid tank. This diluent is, for example, a solvent contained in the photoresist, and is used as a diluent for diluting the photoresist and for improving the wettability (pre-wetting) of the photoresist and the diluted photoresist on the surface of the wafer W Treatment solution.

53 in FIG. 1 is an arm body that supports the diluent supply nozzle 51 at its front end side, and a moving mechanism 54 is connected to the base end side of the arm body 53. The moving mechanism 54 is configured to lift and lower the arm body 53 and move freely in the horizontal direction along the guide rail 55. By the horizontal movement of the moving mechanism 54, the position where the diluent is released on the diameter of the surface of the wafer W can be moved along the diameter direction of the wafer W. A reference numeral 56 in the figure is a standby portion that waits for the thinner supply nozzle 51 to stand by when the wafer W is not being processed. Moreover, in FIG. 1, the space arrange | positioned respectively by the cup body 2 and the standby parts 46 and 56 is exaggerated.

As shown in FIG. 2, a photoresist film forming apparatus 1 is provided with a control unit 10 composed of a computer. In the control section 10, a program is installed, and the program is stored in a recording medium such as a floppy disk, an optical disk, a hard disk, an MO (Magneto-Optical Disk), and a memory card. The installed program is programmed with instructions (each step) to transmit control signals to each part of the photoresist film forming apparatus 1 to control its operation. Specifically, the following operations are controlled by the program: the change of the rotation speed of the wafer W by the rotating mechanism 12, the movement of the photoresist supply nozzle 41 and the diluent supply nozzle 51 provided by the moving mechanisms 44 and 54, and the photoresist liquid from the photoresist liquid. The supply unit 42 stops or supplies the photoresist nozzle 41, and the diluent supplies or stops the diluent supply nozzle 51 from the diluent supply unit 52.

Next, an example of the wafer W processed by the photoresist film forming apparatus 1 will be described with reference to FIG. 3 showing the surface of the wafer W. The wafer W is, for example, a circular substrate having a diameter of 300 mm. As shown in FIG. 3, a plurality of grooves 61 are formed on the surface of the wafer W in a grid pattern. FIG. 4 is a longitudinal section of the wafer W. As shown in FIG. The depth of the trench 61 shown in H1 is, for example, 5 μm to 100 μm, and the width of the trench 61 shown in L0 is, for example, 50 μm to 500 μm.

Next, with regard to the processing steps for forming a photoresist film on the wafer W by the photoresist film forming apparatus 1, a schematic perspective view showing the state of the surface of the wafer W and the operation of each of the nozzles 41 and 51 is referred to. 5 to 10 for explanation. In addition, a schematic view of a longitudinal cross-section of the wafer W is also referred to as necessary, that is, FIGS. 11 to 14.

First, the wafer W described in FIG. 3 is transferred to the photoresist film forming apparatus 1 by a transfer mechanism, and then the center portion of the back surface of the wafer W is sucked and held by the rotary chuck 11 through the lift pin 15. . Then, the wafer W is rotated at, for example, 100 rpm, and the diluent supply nozzle 51 positioned on the center portion of the wafer W is used to release the diluent 50 to the center portion of the wafer W. Then, the rotation speed of the wafer W is increased to, for example, 1000 rpm, and the diluent 50 is extended to the peripheral edge portion of the wafer W by centrifugal force to perform pre-wetting (FIG. 5).

Thereafter, the release of the diluent 50 from the diluent supply nozzle 51 is stopped, the diluent supply nozzle 51 is moved to approach the peripheral edge portion of the wafer W, and the photoresist supply nozzle 41 is disposed on the center portion of the wafer W. Then, the wafer W is rotated at, for example, 10 rpm, and the photoresist 40 is released from the photoresist supply nozzle 41 to the center portion of the wafer W; A circular liquid tank A1 is formed in a plan view (FIG. 6). Thereafter, the release of the photoresist 40 from the supply nozzle 41 is stopped, and the rotation speed of the wafer W is increased to, for example, 200 rpm, and the surface of the liquid pool A1 is flattened by centrifugal force (FIG. 7 and FIG. 11). At this time, since the rotation speed of the wafer W is low, the diffusion of the liquid pool A1 is suppressed, and the peripheral end of the liquid pool A1 does not reach the peripheral end of the wafer W. The distance L1 shown in FIG. 11, that is, the distance L1 from the center of the wafer W to the peripheral end of the liquid pool A1 is, for example, 50 mm. In addition, the photoresist 40 constituting the liquid pool A1 is mixed with the diluent 50 supplied into the groove 61 below the liquid pool A1 by pre-wetting, and enters the groove 61.

Next, the rotation speed of the wafer W is reduced to, for example, 60 rpm, and the diluent 50 is supplied to the peripheral portion of the liquid pool A1 from the diluent supply nozzle 51. Since the wafer W is rotating, the centrifugal force prevents the diluent 50 from flowing from the position supplied to the liquid pool A1 to the center portion side of the wafer W, but from the supplied position to the periphery of the wafer W. Department side. As a result, what is diluted by the diluent 50 is limited to the photoresist 40 constituting the peripheral portion of the liquid pool A1, so that the photoresist 40 has a viscosity lower than the photoresist 40 and has a high fluidity. This diluted photoresist 40 will be labeled as mixed solution A2. Therefore, a state in which the mixed liquid A2 exists around the liquid pool A1 of the photoresist 40 (FIG. 8 and FIG. 12). The distance L2 shown in FIG. 12, that is, the distance L2 from the center of the wafer W to the position where the diluent 50 is supplied, is, for example, 40 mm. In more detail, the position where the diluent 50 is supplied means a region provided on the discharge port of the diluent supply nozzle 51 to project the wafer W in the diluent release direction. In addition, in order to avoid complication of the drawings, in FIG. 11 and FIG. 12, the illustration of the diluent 50 supplied to the peripheral portion of the wafer W due to pre-wetting is omitted.

Next, the release of the diluent 50 is stopped, and the rotation speed of the wafer W is increased to, for example, 1800 rpm. Since the viscosity of the above-mentioned mixed liquid A2 is lower than the photoresist 40 constituting the liquid pool A1, the increase in the centrifugal force caused by the increase in the rotational speed makes the peripheral edge of the wafer W covered with the pre-wet thinner 50 The portion is rapidly extended toward the peripheral end of the wafer W. In this stretching, because the viscosity of the mixed liquid A2 is low as described above, no fingering, that is, branch-like diffusion occurs; therefore, it will spread extremely evenly along the circumferential direction of the wafer W. Furthermore, it is possible to suppress the formation of a pattern called a striation. In addition, as described above, due to the low viscosity, the mixed liquid A2 enters the groove 61 of the recessed portion, and the mixed liquid A2 fills the groove 61. More specifically, the mixed liquid A2 is caused to enter the groove 61 by being mixed with the diluent 50 which has entered the groove 61 due to pre-wetting.

In this way, the extension of the mixed liquid A2 is advanced, so that the entire peripheral portion of the wafer W is covered by the mixed liquid A2 (FIG. 9 and FIG. 13). While the coating of the mixed liquid A2 is advanced, the liquid pool A1 formed by the photoresist 40 is also extended toward the peripheral end of the wafer W. Since the viscosity of the photoresist 40 is higher than that of the mixed liquid A2, the speed at which the outer edge of the liquid pool A1 moves is slower than the speed of the mixed liquid A2. Therefore, in order to extend the photoresist 40 to the peripheral edge portion of the wafer W that has been covered by the mixed liquid A2, the outer edge of the liquid pool A1 will be mixed with the mixed liquid A2 and face the peripheral end of the wafer W. Therefore, drying of the liquid pool A1 during stretching is suppressed, and the liquid pool A1 does not diverge and spreads extremely evenly along the circumferential direction of the wafer W. In this way, during the continuous stretching, the photoresist 40 constituting the liquid pool A1 located on the groove 61 will enter the groove 61 by being mixed with the mixed liquid A2 in the groove 61.

As shown in FIG. 14, after the outer edge of the liquid pool A1 reaches the peripheral end of the wafer W, and the entire surface of the wafer W is covered by the photoresist 40, the wafer W also continues to rotate; until the photoresist 40 is dried, A photoresist film 60 is formed (FIG. 10). Then, the wafer W stops rotating, and the film forming process is ended. After that, the wafer W is carried out from the photoresist film forming apparatus 1 by the operation of raising and lowering the ejector pin 15 and the conveyance mechanism.

In order to clearly show the effect of the processing described in FIGS. 5 to 14 (processing of the embodiment of the present invention), FIG. 15 and FIG. 16 showing the state of the photoresist 40 are used to explain the following processing as Comparative Example: After the liquid pool A1 of the photoresist 40 is formed, a photoresist film is formed without supplying a diluent 50 to the peripheral portion of the liquid pool A1. The processing of this comparative example is the same as that of the embodiment of the present invention except that the diluent 50 is not supplied to the peripheral portion of the liquid pool A1.

As described with reference to FIGS. 5 to 7, after the pre-wetting to form the liquid pool A1 of the photoresist 40, the rotation speed of the wafer W is increased in order to stretch the liquid pool A1 (FIG. 15). During the extension of the liquid pool A1, the above-mentioned bifurcation occurs because the outer edge of the liquid pool A1 will dry and the viscosity of the photoresist 40 rises. In the dotted line frame of FIG. 16, the branches of the photoresist 40 of the branch are shown when viewed from the peripheral end of the wafer W toward the center. When the branch of the photoresist 40 is diffused, it will be drawn into the air on the surface of the wafer W. In addition, since the photoresist 40 has a high viscosity, the photoresist 40 is not sufficiently filled in the trench 61, but is maintained in an air-containing state, so that the upper part of the trench 61 is blocked. The air entrained in the photoresist 40 and the air remaining in the groove 61 become bubbles 62 and are contained in the photoresist film 60. In the treatment of this comparative example, the diluent 50 was supplied to the peripheral portion of the wafer W due to pre-wetting before the liquid pool A1 was formed; however, it was confirmed that the bubbles could not be sufficiently suppressed as shown in the evaluation test described later 62 Mixed in. It is presumed that this is due to the volatilization of the diluent 50 being promoted because the wafer W is rotated at a higher rotation speed during the stretching of the liquid pool A1.

If the processing of the embodiment of the present invention described with reference to FIGS. 5 to 14 is described above, after the liquid pool A1 of the photoresist 40 is formed at the center of the wafer W, it is limited to the periphery of the liquid pool A1. The diluent 50 is supplied to form the mixed liquid A2, and then the peripheral portion of the wafer W is covered with the mixed liquid A2 by the centrifugal force of the rotation of the wafer W; and further, the central portion of the liquid pool A1 is formed. The photoresist 40 is extended to the periphery of the wafer W to form a photoresist film 60. Since the photoresist 40 constituting the liquid pool A1 is mixed with the mixed liquid A2 supplied to the peripheral portion of the wafer W first, and then stretches toward the peripheral end of the wafer W, the viscosity of the photoresist 40 due to drying can be suppressed. rise. Therefore, the faults described in Figures 15 and 16-that is, the photoresist 40 is branched and diffused irregularly, causing air to enter the photoresist 40; or because the photoresist 40 is not charged into the groove 61, Residual air in the groove 61-can be prevented. As a result, it is possible to prevent bubbles from being mixed into the photoresist film 60. Furthermore, since the thinner 50 is limited to the peripheral portion of the liquid cell A1 of the photoresist 40, the photoresist 40 can be prevented from being diluted excessively. Therefore, the controllability of the film thickness of the photoresist film 60 can be improved, and the photoresist film 60 can be formed to have a large film thickness.

It is also conceivable that the mixed liquid A2 is supplied to the peripheral portion of the wafer W by replacing the diluent 50 with the mixed liquid A2 for pre-wetting. After this pre-wetting, as shown in FIG. 15 and FIG. 16, Without supplying the diluent 50 to the liquid pool A1 of the photoresist 40, the liquid pool A1 is extended to the peripheral edge portion of the wafer W. However, in this case, after the mixed liquid A2 is supplied to the wafer W, until the photoresist 40 is released to the wafer W and extended to the peripheral edge portion of the wafer W, the diluent 50 in the mixed liquid A2 may volatilize. Yu. Moreover, because the mixed liquid A2 needs to be stored in the liquid tank in advance, and then the mixed liquid A2 of the liquid tank is released from the nozzle to the wafer W; therefore, in the case of performing such pre-wetting, the storage to liquid Before the tank, it is necessary to adjust the mixed liquid A2 first, so it is labor-intensive. In contrast, in the process of the embodiment of the present invention described with reference to FIGS. 5 to 14, the mixed liquid A2 is formed in a state where the photoresist 40 has been supplied to the wafer W, and then the mixed liquid A2 and the light can be quickly made. The resistance 40 extends to the peripheral edge portion of the wafer W. Therefore, the volatilization of the diluent 50 in the mixed solution A2 can be suppressed, and the viscosity increase of the photoresist 40 subjected to stretching can be reliably suppressed; and the coating solution 40 does not need to be adjusted before the coating process of the photoresist 40 is required. In other words, the processing of the embodiment of the present invention described above has advantages.

At this point in the process of the embodiment of the present invention, if the release time of the diluent 50 is too long, the mixed solution A2 will be removed from the surface of the wafer W, and the photoresist 40 will be extended to the diluent 50. The peripheral edge portion of the covered wafer W; however, since the diluent 50 is more volatile than the mixed liquid A2, it is difficult to obtain the above-mentioned effect. Furthermore, if the release time of the diluent 50 is too short, the viscosity of the mixed liquid A2 cannot be sufficiently reduced, and there is a possibility that the mixed liquid A2 may not have sufficient covering properties with respect to the wafer W. In order to prevent these defects from occurring, the release time of the diluent 50 is appropriately set, for example, the release time is 1 second to 30 seconds; in the above process, the diluent is released in 20 seconds.

Furthermore, in the process of the embodiment of the present invention described above, after stopping the release of the diluent 50, in order to extend the mixed liquid A2 and the photoresist 40, the rotation speed of the wafer W is increased; During the ascent, the release of the diluent 50 is continued, and the diluent is supplied to the liquid pool A1 of the photoresist 40 in the extension. In the case where the diluent is also supplied during the increase in the rotation speed of the wafer W as described above, for example, it may be at the time point when the stretched mixed liquid A2 reaches the peripheral end of the wafer W, or when it reaches the peripheral end After that, the release of the diluent 50 is stopped again, so that the peripheral edge portion of the wafer W is surely covered with the mixed liquid A2.

Furthermore, in the process of the embodiment of the present invention described above, in order to make the surface of the liquid pool A1 of the photoresistor 40 flat and the rotation speed of the wafer W becomes 200 rpm, the diluent 50 is supplied to the liquid bath A1 of the photoresist 40 When the mixed solution A2 is formed, the wafer W is rotated at 60 rpm. The reason why the rotation speed is so reduced is that if the rotation speed of the wafer W is too large when the diluent 50 is supplied, the drying of the formed mixed liquid A2 will progress more, and the liquid in the photoresist 40 will be stretched. In the case of cell A1, the viscosity reduction of liquid cell A1 is insufficient. However, the rotation speed of the wafer W when the diluent 50 is supplied is not limited to 60 rpm. However, from the viewpoint of suppressing the drying of the mixed solution A2 as described above, it is preferably 500 rpm or less. For example, when the viscosity of the photoresist is 500 cP, it can be 20 rpm; when it is 5000 cP, it can also be 500 rpm.

After the diluent 50 is supplied and the mixed liquid A2 and the liquid pool A1 are stretched, in order to increase the centrifugal force to perform such stretching, as described above, the rotation speed of the wafer W is increased. That is, the rotation speed (first rotation speed) of the wafer W when the diluent 50 is released in order to form the mixed liquid A2 is lower than the rotation speed (second rotation speed) when the mixed liquid A2 and the liquid pool A1 are stretched. .

At this point in the process of the embodiment of the present invention, although the diluent 50 is released to form the mixed liquid A2, the diluent supply nozzle 51 is caused to stand still. The diluent supply nozzle 51 is moved by the moving mechanism 54 to move the release position of the diluent 50 along the diameter direction of the wafer W (that is, the diameter direction of the liquid pool A1 and the mixed liquid A2). Specifically, for example, as shown in FIG. 17, in a state where the diluent 50 is released from the diluent supply nozzle 51 toward the rotating wafer W, the diluent supply nozzle can be provided on the peripheral portion of the liquid pool A1. 51 moves from the peripheral end side of the wafer W toward the center side, and is limited to supplying the diluent 50 to the peripheral edge portion of the liquid pool A1 to form the mixed liquid A2. In this way, by moving the diluent supply nozzle 51 to move the liquid flow of the diluent 50, the photoresist 40 constituting the peripheral portion of the liquid pool A1 is further stirred together with the diluent 50, and the formed mixture can be mixed. The viscosity of the liquid A2 did decrease. As a result, the mixed liquid A2 can more reliably cover the entire peripheral edge portion of the wafer W, and can prevent bubbles from being mixed into the photoresist film 60.

In the example shown in FIG. 17, the release of the diluent 50 is started outside the vicinity of the liquid pool A1. The diluent supply nozzle 51 is maintained in a state where the diluent 50 is released, and moves to the position of the liquid pool A1. A thinner 50 is supplied to the peripheral portion. The reason why the starting position of the diluent 50 is set in this way is to prevent the air between the diluent supply nozzle 51 and the wafer W from receiving the diluent released from the diluent supply nozzle 51. In the case of a pressure of 50, it is mixed into the liquid pool A1. When the mixed liquid A2 is formed, the diluent supply nozzle 51 in a state where the diluent 50 is released may be moved from the center side of the wafer W to the peripheral end portion side. That is, the diluent supply nozzle 51 may be moved in a direction opposite to the direction shown in FIG. 17.

When the mixed liquid A2 and the liquid pool A1 are extended to the peripheral edge portion of the wafer W, the diluent 50 from the diluent supply nozzle 51 may be released and the diluent supply nozzle 51 may be moved. In this case, the operation of the diluent supply nozzle 51 can be controlled as described below, for example. First, as illustrated in FIG. 12, the diluent 50 is released toward the peripheral portion of the liquid pool A1 of the photoresist 40 to form a mixed liquid A2. After that, while maintaining the state where the diluent 50 is released, the rotation speed of the wafer W is increased in the same manner as in the aforementioned processing example, so that the liquid pool A1 is extended toward the peripheral end of the wafer W.

At this time, the diluent supply nozzle 51 is moved so that the position where the diluent 50 is supplied on the wafer W will correspond to the position of the end portion of the liquid pool A1 that is stretched. Specifically, for example, as shown in FIGS. 18 and 19, the diluent supply nozzle 51 is moved to the peripheral edge portion side of the wafer W at a speed equal to the moving speed of the end portion of the liquid pool A1, and the diluent 50 is continued. Release to the end of the extended pool A1. By moving the diluent supply nozzle 51 in this way, the end of the liquid pool A1 moves as if it follows the release position of the diluent 50 on the wafer W. While the liquid pool A1 is being stretched, Under the observation of the liquid pool A1, a new mixed liquid A2 is continuously generated immediately in front. By supplying the diluent 50 in this manner, the drying of the liquid pool A1 during stretching can be more surely suppressed.

Further, as shown in FIG. 20, even when the moving speed of the diluent supply nozzle 51 is set to be higher than the moving speed of the end of the liquid pool A1, the mixed liquid in front of the moving liquid A1 end A2, contains a lot of diluent 50, so it can suppress the drying of liquid tank A1. As shown in FIG. 18 to FIG. 20, when the diluent supply nozzle 51 is moved, the release of the diluent 50 can be performed until the release position of the diluent 50 reaches the peripheral end of the wafer W; The release of the diluent 50 is stopped before reaching the peripheral end. In addition, to change the position where the diluent 50 is released along the diameter direction of the wafer W as described above is not limited to moving the diluent supply nozzle 51 in the horizontal direction. For example, the arm body 53 may be provided with a changed diluent. The inclination adjustment mechanism of the inclination of the supply nozzle 51 changes the inclination of the diluent supply nozzle 51.

At this point, the diluent of the photoresist is explained in more detail as follows: As this diluent, as long as it has solubility with respect to the chemical components constituting the photoresist, it can be mixed with the photoresist, and the light can be reduced by mixing Resistance of the viscosity of the liquid. Furthermore, the pre-wet processing solution is described in more detail as follows: In order to improve the wettability of the photoresist 40 supplied to the center portion of the wafer W on the surface of the wafer W, the photoresist It enters the groove 61, so it is the same as the above-mentioned diluent, as long as it has a solubility with respect to the chemical components constituting the photoresist, and it can be mixed with the photoresist, and it can be mixed to reduce the viscosity of the photoresist. use. Therefore, as the diluent and the pre-wetting treatment liquid, for example, an organic solvent not contained in the photoresist may be used. Furthermore, these dilution liquids and pre-wetting treatment liquids may be liquids composed of different compounds.

In the above-mentioned process of the embodiment of the present invention, a photoresist film is formed on the surface of the wafer W where the groove 61 is formed as a recess; however, a photoresist film is formed on the surface of the wafer W where the recess is not formed. In the case, the processing of this embodiment is also effective. The diluent supply nozzle 51 is not limited to releasing the liquid stream of the diluent 50 as in the aforementioned example, and may also release the water-diluent diluent 50 or the vapor of the diluent 50. However, in order to dilute the photoresist quickly and sufficiently, it is preferable to release the liquid stream. The diluent is not limited to be continuously supplied, and may be intermittently supplied. Furthermore, when the diluent is supplied to the peripheral portion of the liquid pool A1, the diluent can also be supplied from a plurality of nozzles arranged along the circumferential direction of the wafer W. Therefore, when the diluent is supplied, the wafer W can also be supplied. Is at rest.

The present invention is also applicable to a case where a coating film other than a photoresist film is formed. For example, the present invention can also be applied to a case where a coating liquid for forming an antireflection film or a coating liquid for forming an insulating film is applied on the surface of a substrate to form an antireflection film or an insulating film. The various embodiments described above may be changed or combined with each other as appropriate.

(Evaluation Test)-Evaluation Test 1 The evaluation test performed in accordance with the present invention will be described. As the evaluation test 1-1, a photoresist film 60 is formed on the wafer W according to the procedure described as the process of the embodiment of the present invention described above. As the evaluation test 1-2, after the formation of the pre-wet, photoresist 40 liquid pool A1 described in FIG. 5 to FIG. 7 in order, the diluent 50 was supplied to the outside of the liquid pool A1, and then the wafer was made. The rotation speed of W is increased to extend the liquid pool A1 to the peripheral edge portion of the wafer W to form a photoresist film 60. That is, in the evaluation test 1-2, instead of the mixed liquid A2, the state of the peripheral portion of the wafer W is covered with the diluent 50 supplied after the formation of the liquid pool A1, so that the liquid pool A1 is extended to the wafer. The periphery of W forms a photoresist film 60. In addition, as the evaluation test 1-3, the following comparative example processing as described in FIG. 15 and FIG. 16 is performed: after the liquid pool A1 is formed, the wafer W is not supplied with the diluent 50 to form a photoresist Film 60.

After investigating the bubbles contained in the photoresist film 60 formed by the evaluation tests 1-1 to 1-3, it was found that in the evaluation test 1-3, the photoresist film 60 was contained in the peripheral portion of the wafer W More bubbles. In the evaluation test 1-2, although there are fewer systems than the evaluation test 1-3, the photoresist film 60 contains bubbles in the peripheral portion of the wafer W. In the evaluation test 1-1, almost no air bubbles were found in the photoresist film 60. Therefore, based on this evaluation test, it was confirmed that the treatment of the embodiment of the present invention described above has an effect on suppressing the incorporation of air bubbles into the photoresist film 60.

Furthermore, for the photoresist film 60 formed in the evaluation test 1-1 and the photoresist film 60 formed in the evaluation test 1-3, the films at plural positions along the diameter direction of the wafer W were measured. thick. In the graph of FIG. 21, the measurement results of the wafer W of the evaluation test 1-1 are represented by solid lines, and the measurement results of the wafer W of the evaluation test 1-3 are represented by dotted lines. The vertical axis of the graph represents the measured film thickness (unit: μm), and the horizontal axis of the graph represents each position of the diameter of the wafer W where the film thickness is measured by a number of 0 to 50. The horizontal axis is further described as follows: the smaller the number, the position on one end side of the wafer W; the other end of the 0 wafer W and the other end of the 50 wafer W. As shown in this graph, between the evaluation test 1-1 and the evaluation test 1-3, there is no significant difference in the film thickness at each measurement position. Therefore, it can be seen that the reduction in film thickness caused by the treatment of supplying the diluent to the liquid pool A1 in the evaluation test 1-1 can be suppressed.

Furthermore, for the photoresist film 60 formed in the evaluation test 1-1 and the photoresist film 60 formed in the evaluation test 1-3, the film thicknesses of many parts in the plane were measured, and the film thicknesses were calculated. Non-uniformity. Specifically, the non-uniformity of this film thickness is calculated by the following formula 1. The smaller the number 値 of this non-uniformity of the film thickness, the smaller the film thickness drop within the surface of the wafer W. The film thickness non-uniformity of the photoresist film formed in the evaluation test 1-1 is 4.43%, which is smaller than the film thickness non-uniformity of the photoresist film formed in the evaluation test 1-3, that is, 8.0%. Therefore, it is obvious that if the method of evaluation test 1-1 is used, the uniformity of the film thickness of the photoresist film 60 in the W plane of the wafer can be improved. Non-uniformity of film thickness (%) = ((maximum film thickness measured-minimum film thickness measured) / average film thickness measured) × 100 ... Formula 1

1‧‧‧Photoresist film forming device
10‧‧‧Control Department
11‧‧‧ Rotating Chuck
12‧‧‧ rotating mechanism
13‧‧‧Shaft
14‧‧‧ round plate
15‧‧‧Elevating thimble
16‧‧‧Lifting mechanism
2‧‧‧ cup body
21‧‧‧Mountain Guide
22‧‧‧Vertical Wall
23‧‧‧ tube
24‧‧‧ middle guide
25‧‧‧ opening
26‧‧‧ tube
27‧‧‧inclined wall
31‧‧‧Liquid receiving department
32‧‧‧ Drainage Road
33‧‧‧Exhaust pipe
40‧‧‧Photoresist
41‧‧‧Photoresistive nozzle
42‧‧‧Photoresistance Supply Department
43‧‧‧arm body
44‧‧‧ mobile agency
45‧‧‧rail
46‧‧‧Standby
50‧‧‧ thinner
51‧‧‧ thinner supply nozzle
52‧‧‧ Thinner Supply Department
53‧‧‧arm body
54‧‧‧ Mobile agency
55‧‧‧rail
56‧‧‧Standby
60‧‧‧Photoresistive film
61‧‧‧Groove
62‧‧‧ Bubble
A1‧‧‧Liquid Pool
A2‧‧‧ mixed liquid
H1‧‧‧ Depth of groove
L0‧‧‧Width of groove
L1‧‧‧The distance from the center of the wafer to the periphery of the liquid pool
L2‧‧‧Distance from the center of the wafer to the position where the diluent is supplied
W‧‧‧ Wafer

[FIG. 1] A perspective view of a photoresist film forming apparatus according to an embodiment of the present invention. FIG. 2 is a plan view of the photoresist film forming apparatus. [Fig. 3] A plan view showing an example of a wafer processed by the aforementioned photoresist film forming apparatus. Fig. 4 is a longitudinal sectional side view of the wafer. 5 is a schematic perspective view showing a step of forming a photoresist film on the wafer. 6 is a schematic perspective view showing a step of forming a photoresist film on the wafer. FIG. 7 is a schematic perspective view showing a step of forming a photoresist film on the wafer. FIG. 8 is a schematic perspective view illustrating a step of forming a photoresist film on the wafer. FIG. 9 is a schematic perspective view illustrating a step of forming a photoresist film on the wafer. FIG. 10 is a schematic perspective view showing a step of forming a photoresist film on the wafer. [Fig. 11] A longitudinal cross-sectional side view of a wafer used to illustrate a photoresist stretching situation. [Fig. 12] A longitudinal cross-sectional side view of a wafer used to illustrate a photoresist stretching situation. [Fig. 13] A longitudinal sectional side view of a wafer used to illustrate a photoresist stretching situation. [Fig. 14] A longitudinal cross-sectional side view of a wafer used to illustrate a photoresist stretching situation. [Fig. 15] A longitudinal sectional side view for explaining a wafer processed in a comparative example. [Fig. 16] A longitudinal sectional side view for explaining a wafer processed in a comparative example. [Fig. 17] A longitudinal sectional side view of a wafer used to illustrate a scenario of diluting a photoresist. [FIG. 18] A longitudinal cross-sectional side view of a wafer used to illustrate a scenario of diluting a photoresist. [Fig. 19] A vertical cross-sectional side view of a wafer used to illustrate a scenario of diluting a photoresist. [Fig. 20] A vertical cross-sectional side view of a wafer used to illustrate a scenario of diluting a photoresist. [Fig. 21] A graph showing the results of the evaluation test.

11‧‧‧ Rotating Chuck

40‧‧‧Photoresist

50‧‧‧ thinner

51‧‧‧ thinner supply nozzle

A1‧‧‧Liquid Pool

A2‧‧‧ mixed liquid

W‧‧‧ Wafer

Claims (8)

A coating film forming device includes: a substrate holding portion that horizontally holds a substrate; a rotating mechanism that rotates the substrate held by the substrate holding portion; a coating liquid supply nozzle that supplies a center portion of the substrate to the substrate; A coating liquid for forming a coating film on the surface; a dilution liquid supply nozzle for supplying a dilution liquid for reducing the viscosity of the coating liquid to the substrate to form a mixed liquid obtained by diluting the coating liquid; and a control unit that outputs the first Control signals of step, second step, and third step; the first step is to supply the coating liquid to the substrate to locally form a liquid pool at the center portion of the substrate; then, the second step, It is limited to supplying a diluent to the peripheral portion of the liquid pool to form a mixed liquid. Next, in the third step, the substrate is rotated to extend the mixed liquid to the peripheral portion of the substrate by centrifugal force, and the The mixed liquid covers the peripheral edge portion of the substrate, and the liquid pool is extended to the peripheral edge portion of the substrate covered by the mixed liquid to form the coating film. For example, the coating film forming apparatus of the first patent application range, wherein the viscosity of the coating liquid is 500 cP to 5000 cP. For example, the coating film forming apparatus according to item 1 or 2 of the patent application scope, wherein the second step includes a step of rotating the substrate at a first rotation speed; the third step includes a step at a higher speed than the first rotation speed. 2 rotation speed to rotate the substrate. For example, the coating film forming apparatus according to item 1 or 2 of the patent application scope, wherein a nozzle moving mechanism is provided to move the diluent supply nozzle; the second step includes moving the diluent supply nozzle by the nozzle moving mechanism A step of moving the position of supplying the diluent on the surface of the substrate along the diameter direction of the liquid pool. For example, the coating film forming apparatus according to item 4 of the patent application scope, wherein the second step includes the following steps: a step of supplying the diluent to the outside of the liquid pool of the coating liquid in the substrate; and then, making the The step of moving the diluent supply nozzle so that the position where the diluent is supplied in the rotating substrate is toward the center of the liquid pool of the coating liquid, and supplying the diluent to the peripheral portion of the liquid pool of the coating liquid. For example, the coating film forming apparatus according to item 1 or 2 of the patent application scope, wherein the third step includes the following steps: a step of supplying the diluent from the diluent supply nozzle; and the diluent by the nozzle moving mechanism. The liquid supply nozzle is moved, and a step of moving the position where the diluent is supplied on the surface of the substrate from the center portion side to the peripheral portion side of the substrate corresponding to the position of the end portion of the liquid pool that is stretched is ordered. A coating film forming method includes the following steps: a step of horizontally holding a substrate by a substrate holding portion; and then, supplying a coating liquid for forming a coating film on a surface of the substrate through a coating liquid supply nozzle to the substrate to A step of forming a liquid pool locally at the center portion of the substrate; thereafter, a dilution liquid supply nozzle is used to supply a dilution liquid for reducing the viscosity of the coating liquid to the peripheral portion of the liquid pool to form the coating liquid. A step of forming a mixed liquid; and then, rotating the substrate by a rotating mechanism that rotates the substrate through the substrate holding portion, so that the mixed liquid is extended toward a peripheral edge portion of the substrate by centrifugal force, and covered with the mixed liquid The coating film is formed by extending a peripheral portion of the substrate to the peripheral portion of the substrate covered by the mixed liquid. A recording medium stores a computer program for forming a coating film forming device for forming a coating film on a substrate; the computer program includes a group of steps for implementing the coating film forming method of claim 7 in the scope of patent application.