JP6448064B2 - Cover plate for defect control in spin coating - Google Patents

Description

  The techniques disclosed herein relate to spin coating systems and processes, including spin coating of semiconductor substrates.

  Spin coating has been used for decades as a method of coating flat surfaces with polymers, photoresists, and other compounds. Spin coating is typically performed by depositing a solvent solution, polymer solution, or other liquid material on a flat substrate. The substrate is then rotated at an angular velocity sufficient to generate a centrifugal force that causes the solution to flow outward toward the edge of the substrate, thereby coating the entire surface of the substrate. Excess solution is expelled from the edge of the substrate, and the remaining solution becomes thinner and harder as the solution evaporates, leaving a thin polymer film.

  Such spin coating is a process commonly performed in lithography used in semiconductor device manufacturing. In the example of the photolithography process, a resist spin coating process is performed to form a uniform resist film on the semiconductor wafer. Next, typically, the resist film is exposed to light or other radiation through a mask for forming a latent line pattern by an exposure process. Finally, in the development process, the wafer coated with the resist after the exposure process is developed to reveal the line pattern. Such a series of processing stages is typically performed in a coating development system.

  In a typical spin coating process, a semiconductor wafer or other substrate is rotated with a spin chuck by a rotational drive mechanism. The wafer can be secured to the spin chuck by vacuum suction or held in other ways. The resist nozzle positioned above the semiconductor wafer drops the resist solution onto the center of the wafer surface. The dropped resist solution spreads radially outward toward the periphery of the semiconductor wafer by centrifugal force when the wafer is spinning. Spreading the resist over the entire wafer surface occurs relatively quickly, but the semiconductor wafer is continuously rotated for a while (usually at a reduced rotation speed) to spin off and dry the resist solution spread on the wafer surface. Let Such spin coating is widely used in the semiconductor industry and forms a thin, uniform layer of photoresist polymer primarily on the surface of the wafer as a preparatory step for further wafer processing.

  A common desire in semiconductor manufacturing and spin coating is to have high throughput. During semiconductor manufacturing, the wafer may go through multiple coating and development steps. Therefore, throughput can be improved if the processing time to complete each spin coating on the wafer is minimized. In other words, it is desirable to complete the spin coating or spinning process in the shortest possible time and increase the number of wafers that can be processed per unit time. The difficulty with increasing throughput is meeting the requirements of uniformity and quality. In a typical spin coating process that uses rotation to both spread the liquid material across the wafer and dry the liquid material, the drying time continues substantially longer than the spreading time. There are various techniques that can be used to stop the drying time. One basic technique is to increase the rotational speed of the wafer, which in turn increases the fluid flow rate across the surface of the wafer. That is, the faster the wafer rotates, the faster the liquid resist or other liquid chemistry will dry (solvent evaporates).

  However, higher substrate rotation speeds can result in coating non-uniformities and / or defects. These defects are typically the result of turbulence over the surface of the wafer triggered by a relatively higher rotational speed. One identified problem due to the greater rotational speed of the substrate is the formation of wind marks, also known as the Ekman spiral. This is a phenomenon that occurs when the wafer continuously rotates at a higher angular velocity until the fluid flow (air and solvent) above the wafer transitions from laminar to turbulent. There is a strong secondary flow that causes a spiral pattern on the surface of the photoresist just before full turbulence occurs. These patterns (wind marks) cause defects in subsequent processing steps due to the lack of uniformity of resist thickness.

  For a given substrate diameter, there is a maximum speed at which the airflow can exceed the threshold and the wafer can be rotated without forming a window mark in the resist. The threshold for forming the wind mark is based on a combination of diameter and angular velocity. The start of the windmark is associated with a specific value for the Reynolds number. The Reynolds number for spin coating quantifies inertial and viscous forces using the air density above the wafer, the angular velocity of the wafer, the radial position from the center of the wafer, and the viscosity of the air. The critical Reynolds number identifies the point where instability occurs. With the wind mark, the critical Reynolds number determines the limit of angular velocity based on the edge radius of a given wafer W. As the diameter of the substrate increases, the maximum angular velocity needs to be reduced due to an increase in tangential velocity at a radial distance far from the rotation axis. In other words, when spinning a larger disk, the spin rate needs to be reduced to prevent wind marks near the edge of the wafer.

  This is particularly difficult when the semiconductor industry moves from processing 300 mm diameter wafers to processing 450 mm diameter wafers. For example, some conventional spin coating systems for coating 300 mm wafers can spin the wafer to about 1800 revolutions per minute (rpm), dispensing and spreading the liquid in just over a few seconds Evaporate the solvent well in less than about 1 minute (depending on the chemical). However, when the substrate diameter increases to 450 mm, the spin speed needs to be lowered to around 900 rpm in order to avoid wind marks. Such speed reduction has two important difficulties. One difficulty is that at such relatively low rotational speeds, the liquid does not spread evenly across the wafer surface (low centrifugal force). Another challenge with lower rotational speed is that the drying time increases dramatically. At lower rotational speeds, solvent evaporation can take more than 3, 4 minutes or more, which is more than twice the area of a 300 mm wafer, but a 450 mm wafer per unit area of the wafer. This means that the throughput time may actually fall.

  The technology disclosed herein provides a spin coating apparatus and method that prevents the formation of wind marks and other defects due to fluid turbulence, thereby increasing rotational speed while maintaining film uniformity. It is possible to increase the time and shorten the drying time. The techniques disclosed herein include a fluid flow member, such as a ring or cover, positioned or suspended above a substrate holder, rather than above a top surface of a wafer or other substrate. The fluid flow member has a radial curvature that prevents wind marks during rotation of the wafer or other substrate.

  One embodiment includes a spin coating apparatus having a substrate holder configured to hold a substrate in a horizontal direction during a spin coating process, such as by using vacuum suction. A rotation mechanism such as a motor is connected to the substrate holder. The rotation mechanism is configured to rotate the substrate holder about the rotation axis. The apparatus includes a liquid dispenser. The liquid dispenser includes a liquid dispenser configured to dispense a liquid material onto the work surface of the substrate when the substrate is placed in the substrate holder. The work surface is generally planar and is located opposite the bottom surface of the substrate that contacts the substrate holder. The apparatus includes a fluid flow member having a substrate facing surface. The fluid flow member is configured to be positioned so that the substrate facing surface is positioned vertically above the work surface of the substrate when the substrate is placed on the substrate holder. At least a portion of the substrate facing surface is curved such that a given vertical distance between the substrate facing surface and the workpiece surface changes radially relative to a given radial distance from the axis of rotation. In other words, the work surface of the substrate is generally planar, while the fluid flow member suspended above is bent, so the given height of the substrate facing surface above the work surface is Depends on the given radius.

  Other embodiments include a method of manufacturing a semiconductor device. The method has a plurality of steps including positioning the substrate on the substrate holder. The substrate holder holds the substrate in the horizontal direction and has a rotation axis. The substrate has a bottom surface that contacts the substrate holder and a work surface on the opposite side of the bottom surface. In another step, the fluid flow member is positioned above the substrate holder. The fluid flow member has a substrate facing surface positioned above the work surface in the vertical direction at a predetermined average vertical distance or average height above the work surface. At least a portion of the substrate facing surface is curved such that a given vertical distance between the substrate facing surface and the workpiece surface changes radially relative to a given radial distance from the axis of rotation. . Liquid material is dispensed onto the work surface of the substrate via a liquid dispenser positioned above the substrate. The substrate and the substrate holder are spun together via a rotating mechanism coupled to the substrate holder so that the liquid material spreads across the work surface of the substrate and then is dried by a rotating action.

  Of course, the order of description of the various steps as disclosed herein is presented for purposes of clarity. In general, these steps can be performed in any suitable order. Additionally, each of the various features, techniques, configurations, etc. herein may be described at various points in this disclosure, but the concepts may be implemented independently of one another or in combination with one another. . Accordingly, the present invention is implemented and evaluated in different ways.

  It should be noted that this summary does not identify every embodiment and / or additional novel aspect of the disclosure or claimed invention. Instead, the summary of the invention only provides a preliminary discussion of various embodiments and corresponding novel points over the prior art. For additional details and / or possible aspects of the invention and embodiments, the reader is directed to the detailed description section of the present disclosure and the corresponding drawings, which are further described below.

  A more complete understanding of the various embodiments of the present invention and the many attendant advantages will become readily apparent with reference to the following detailed description considered in conjunction with the accompanying drawings. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the embodiments, principles and concepts.

FIG. 1 is a cross-sectional view showing the overall structure of the spin coating apparatus.

FIG. 2 is a top view of the spin coating apparatus of FIG.

FIG. 3 is an enlarged cross-sectional view of a fluid flow member, according to an embodiment herein.

FIG. 4 is an enlarged cross-sectional view of a fluid flow member, according to an embodiment herein.

FIG. 5 is a cross-sectional view of another embodiment of a fluid flow member as described herein.

FIG. 6A is a top view of another embodiment of a fluid flow member as described herein. FIG. 6B is a top view of another embodiment of a fluid flow member as described herein. FIG. 6C is a top view of another embodiment of a fluid flow member as described herein.

FIG. 7 is a top view of another embodiment of a fluid flow member as described herein.

FIG. 8A is a top view of another embodiment of a fluid flow member as described herein. FIG. 8B is a top view of another embodiment of a fluid flow member as described herein.

FIG. 9 is a top view of another embodiment of a fluid flow member having adjustable openings as described herein.

FIG. 10 is a side view of another embodiment of a fluid flow member having adjustable openings as described herein.

FIG. 11 is an exploded perspective view of another embodiment of a fluid flow member having an adjustable opening as described herein.

  For purposes of non-limiting description, the following description specifies specific details such as the specific geometry of the processing system, descriptions of the various components, and the processes used therein. However, it should be understood that the invention may be practiced in other embodiments that depart from these specific details.

  Similarly, for purposes of explanation, specific numbers, materials and configurations are set forth in order to provide a thorough understanding of the present invention. Nevertheless, the present invention may be practiced without specific details. Further, the various embodiments shown in the drawings are understood to be illustrative and not necessarily to scale.

  The various operations will be described as a plurality of discrete operations in sequence, in the most useful manner in understanding the present invention. However, the order of description should not be interpreted as implying that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation. The operations described may be performed in a different order than in the described embodiments. Various additional operations may be performed and / or described operations may be omitted in additional embodiments.

  As used herein, “substrate” generally refers to an object that is processed in accordance with the present invention. The substrate may comprise any material portion or structure of a device, in particular a semiconductor or other electronic device. For example, it may be a base substrate structure such as a semiconductor wafer or a layer on or over the base substrate structure such as a thin film. Thus, the substrate is not intended to be limited to any particular base structure, sublayer or overlay layer, whether patterned or unpatterned, rather, any It is considered to include any combination of such layers, base structures, layers and / or base structures. The following description may refer to a particular type of substrate, but this is only for purposes of illustration and not limitation.

  Accordingly, the technology disclosed herein provides a spin coating apparatus and method that prevents the formation of wind marks and other defects caused by fluid turbulence, thereby increasing the rotational speed and drying time. Maintains film uniformity while allowing shortening. The technology disclosed herein includes fluid flow members such as covers, rings, and other airflow structures. The fluid flow member is positioned or suspended above the substrate holder or above the substrate disposed on the substrate holder. The fluid flow member has a radial curvature selected to prevent wind marks and other effects of turbulence during rotation of the wafer or other substrate. The fluid flow member is positioned proximate to the substrate. The shape, size and position of the fluid flow member assists in maintaining fluid laminar flow (typically solvent and air) across the surface of the wafer coated with the liquid material, while reducing the drying time and thickness. And maintain uniformity of the coating in both points of coverage.

  Exemplary embodiments will be described with reference to the accompanying drawings. For convenience, the embodiments herein will be described in the context of using a resist in part of semiconductor manufacturing. However, other liquid materials can be used for spin coating of semiconductor wafers or other common flat substrates. FIG. 1 is a cross-sectional view showing the overall structure of a resist coating unit 100 (COT) (spin coating apparatus). FIG. 2 is a cross-sectional top view showing the overall structure of the resist coating portion 100 (COT) according to one embodiment of the present invention.

  The circular cup (CP) is disposed at the center of the resist coating portion 100. The substrate holder 102 (spin chuck) is disposed in the cup CP. Cup CP captures waste fluid that flows out of the edge of the substrate and flows down into the conduit. The substrate holder 102 is rotated by a rotation mechanism such as a drive motor 103, and a substrate W such as a semiconductor wafer (hereinafter referred to as “wafer”) W is vacuum-sucked on the substrate holder 102. Other semiconductor holding mechanisms can also be used. The drive motor 103 can be disposed in an opening in the cup CP, and can optionally include an elevating mechanism that moves the substrate holder 102 up and down. The elevating mechanism is, for example, an air cylinder, and can include a vertical guide part. The motor includes a cooling part and can be made of a material advantageous for the spin coating process.

  The wafer W can be transferred to the substrate holder 102 by a holding member 109 as a part of a wafer transfer mechanism (not shown). The vertical drive unit lifts the substrate holder 102 that receives the drive motor 103 and / or the wafer W upward. Alternatively, the cup CP can move up and down or spread apart so that the wafer W is placed on the substrate holder 102.

  The liquid dispenser includes a resist nozzle 110 that supplies a resist solution onto the surface of the wafer W. The liquid dispenser is connected to the resist supplier through the resist supply pipe 111. The resist nozzle 110 is detachably attached to the tip of the resist nozzle scanning arm 112 through the nozzle holder 113. The resist nozzle scanning arm 112 is attached to the upper end portion of the vertical support member 115. The vertical support member 115 is movable in the horizontal direction on the guide rail 114 in one direction (Y direction). Therefore, the resist nozzle scanning arm 112 moves in the Y direction together with the vertical support member 115 in the Y direction driving mechanism (not shown). Another mechanism is used to move the resist nozzle 110 in the Z direction and / or the X direction. The resist nozzle 110 may be interchangeable with other resist nozzles of different types or sizes. A solvent atmosphere can be used to prevent the resist solution at the tip of the nozzle from solidifying or deteriorating.

  Application of the resist includes applying a solvent that functions as a thinner to wetting the wafer surface before supplying the resist solution to the wafer surface. This initial solvent can be applied at the resist nozzle 110 or a nozzle mounted adjacent thereto. Solvent and resist may be supplied via one or more connected supply tubes (not shown) and one or more operating arm assemblies.

  The highly efficient dust collecting filter 141 is provided above the wafer W. The temperature and humidity of the air are adjusted by the temperature / humidity controller 142. The air passes through a highly efficient dust collection filter 141 that removes dust. Thereby, clean air is supplied to the resist coating unit (COT) 100. Note, for example, a gas containing solvent for the resist solution may be introduced instead of air.

  A control system or controller (not shown) of the resist coating unit (COT) 100 can be used to control and manage various spin coating operations. The controller can include a processing controller having a CPU, a user interface, and a memory unit. The user interface is connected to the process controller, and the process manager performs a command input operation or the like via a display or the like showing the visualized operation status of the resist coating unit 100 to control the resist coating unit 100. Includes input devices that allow you to. The memory unit is connected to the processing controller. The memory unit stores a recipe having a control program (software) for realizing various processes executed by the resist coating unit (COT) 100 under the control of the process controller, and a plurality of process condition data.

  As a given recipe that is invoked by a command or similar input through the user interface, the resist coating unit (COT) 100 performs the desired process under the control of the process controller. The controller controls, for example, driving of the drive motor 103, a resist supplier, and a solvent supplier. Specifically, the controller controls the drive motor 103 to increase or decrease its rotational speed. The controller also determines the timing of supplying the resist solution from the resist supplier to the resist nozzle 110, the timing of supplying a solvent such as a thinner from the solvent supplier to the solvent nozzle, and the amount and type of the supplied resist solution and solvent. Control.

  Recipes for control programs and processing condition data can be stored on a computer readable medium such as a CD-ROM, hard disk, flexible disk, flash memory, or other recipes via dedicated lines as needed. It may be sent online from the device.

  The resist coating unit 100 also includes a fluid flow member 150. In the embodiment of FIGS. 1 and 2, the fluid flow member 150 is represented as a relatively thin structural member integrated with the cup CP. However, this integration is only one example embodiment. In other embodiments, the fluid flow member 150 can be attached to a superstructure member within the resist coating portion 100, such as attached to the resist nozzle scanning arm 112. In an embodiment when attached to the scanning arm, the fluid flow member 150 can move aside when the wafer W is placed on or removed from the substrate holder 102. In other embodiments, the fluid flow member is mounted adjacent to the cup CP and can include an independent vertical movement mechanism.

  Generally, the fluid flow member 150 provides a substrate facing surface 155 that is at least partially curved in the radial direction with respect to the rotational axis 180 of the substrate holder 102. As a result, when the wafer W is placed on the substrate holder 102, the bent plate or ring is positioned above the wafer W (substrate). The degree of bending is such that the fluid flow member 150 approaches the wafer W at the outer edge 121 of the wafer W as compared to the radial distance approaching the rotation axis. Further, the height direction or vertical direction distance between the fluid flow member 150 and the wafer W increases the movement toward the rotating shaft 180.

  In some embodiments, as shown in FIG. 5 and the like, when the fluid flow member 150 is bent and extended to the rotation shaft 180, the fluid flow member has a conical shape. In other embodiments, as in FIG. 2, etc., the fluid flow member may define an opening above the wafer W that receives resist and air. This allows more air flow to or through the center or opening 157 while allowing better control of the formation of the wind mark at the wafer edge.

  Reference is now made to FIG. Such a substrate (without bumps in the resist where the fluid flow member begins to cover the substrate, which can occur if the cover is completely flat or has a curvature that is too large or too small) The bent member above the wafer) increases the laminar flow of air and solvent over the coated substrate. Such bumps are formed by locally increasing film thickness due to increased evaporation. The bending of the fluid flow member provides a gradual transition from a significantly bent inner ring-shaped section 150-2 to an outer ring-shaped section 150-1 that is generally linear slope or flat.

  The technology used in this fluid flow member includes a process of moving the fluid flow member up and down to prevent defects. For example, an optimum height of the fluid flow member 150 for the wafer can reduce turbulence, but proximity of the fluid flow member during the liquid material (resist) diffusion phase can cause defects. . When the liquid material is first dispensed onto the substrate, there may be some jumping as the liquid diffuses toward the edge of the substrate. If the particles jump and land on a fluid flow member (initially very close to the wafer), the particles then fall back to the substrate and create a defect. Initially, the fluid flow member avoids possible splashing by maintaining the fluid flow member at a sufficiently high position above the wafer W when dispensing the liquid material, and then after the period of particle jumping has ended, The flow member can be lowered to an optimum height. Thereafter, the wafer W can continue to spin dry the liquid material while the fluid flow member promotes laminar flow of the fluid above the surface of the liquid material on the wafer W. As a result, window marks on the resist surface are prevented, thereby maintaining the uniformity of the layers formed on the wafer.

  Several example embodiments will be described. One embodiment includes a spin coating apparatus that coats a substrate such as a wafer W or other substrate such as an LCD (liquid crystal display) substrate. The apparatus includes a substrate holder configured to hold the substrate in a horizontal direction during the spin coating process. Vacuum suction is a typical holding mechanism, but clamping, the use of a recess to receive the substrate, and other holding mechanisms can be used. The rotation mechanism is configured to rotate the substrate on the substrate holder at the same time as rotating the substrate holder about the rotation axis. The apparatus includes a liquid dispenser. The liquid dispenser is configured to dispense a liquid material (such as a resist) onto the work surface of the substrate when the substrate is placed on the substrate holder. FIG. 3 shows an example of the work surface 125. The work surface is planar and is on the opposite side of the bottom surface of the substrate. Here, the bottom surface is in contact with the substrate holder. In other words, when the substrate holder holds the substrate in the horizontal direction, the work surface is the upper surface.

  The apparatus includes a fluid flow member having a substrate facing surface 155. When the substrate is placed on the substrate holder, the fluid flow member is configured to be positioned or suspended such that the substrate facing surface is positioned vertically above the workpiece surface of the substrate. . At least a portion of the substrate facing surface is bent such that a given vertical distance between the substrate facing surface and the work surface changes in a radial direction with respect to a given radial distance from the rotation axis. . In other words, the fluid flow member has a bending state that changes from the edge 121 toward the center of the substrate coinciding with the rotation axis 180.

  In some embodiments, the given vertical distance between the substrate facing surface and the workpiece surface is such that the given vertical distance decreases as the radial distance from the axis of rotation increases. To change. In other words, the fluid flow member becomes higher toward the center of the substrate, while at the edge of the substrate, the fluid flow member becomes lower. The substrate facing surface can be positioned above the ring-shaped portion of the work surface when the work substrate has a circular shape. The ring shape extends from the outer edge of the work surface to a predetermined radial distance from the rotation axis. The fluid flow member defines a circular opening above the circular portion of the work surface extending from the rotation axis to a predetermined radial distance. Therefore, the fluid flow member is suspended above the peripheral portion of the substrate, and the central opening allows air flow from above the dust collection filter 141 and the like.

  In other embodiments, the substrate facing surface has an outer ring-shaped section such as section 150-1 and an inner ring-shaped section such as section 150-2. The inner ring-shaped section is closer to the rotational axis 180 than the outer ring-shaped section. The inner ring-shaped section of the substrate facing surface is curved in the radial direction, while the outer ring-shaped section of the substrate facing surface has a generally linear slope. Thus, above the edge portion of the substrate, the fluid flow member is substantially flat and large enough to appear generally linear, while the significantly curved portion of the fluid flow member is closer to the center of the substrate. A radius can be included.

  In another embodiment, the work surface and substrate facing when the inner ring-shaped section of the substrate facing surface is bent radially while the fluid flow member is positioned vertically above the work surface of the substrate. The outer ring-shaped section of the substrate facing surface is flat so that there is a substantially constant vertical distance between the outer ring-shaped section of the surface. In other words, the inner portion is bent while the outer portion of the fluid flow member has a constant height above the substrate.

  Embodiments can include a vertical movement mechanism configured to increase or decrease the average vertical distance between the substrate facing surface 155 and the work surface 125 when the substrate is disposed on the substrate holder. . The substrate facing surface is at least partially curved so that it has a variable height at any given radial distance (but the circumference of the fluid flow member where the specific radial distance is the same). In the direction is the same height.) Thus, the average vertical distance can be used to identify the vertical movement / position of the fluid flow member above the substrate facing surface. The vertical movement mechanism can be configured to set the vertical distance between the outer ring-shaped section and the work surface to less than about 5 millimeters or less than about 10 millimeters. Hanging the outer ring-shaped section about 10 millimeters can improve laminar flow compared to when it is not covered. Also, making the outer ring-shaped section less than about 5 millimeters, or even less than 3, 4 millimeters, produces dramatically better laminar flow. The inner ring-shaped section of the substrate facing surface can have a first radius of curvature between about 20 millimeters and 90 millimeters.

  In another embodiment, the substrate facing surface is maintained at a predetermined average vertical distance above the work surface for the first period before dispensing the liquid material onto the work surface. This is the initial height chosen to avoid splashing particles on the substrate facing surface. The first period can be made relatively shorter than the total substrate rotation time. For example, this first period can be only 1 to 2 or 3 seconds. Following the start of dispensing of the liquid material, the predetermined average vertical distance is set to the second predetermined average vertical distance for the second period via the vertical movement mechanism. This second period can be relatively longer than the first period. By way of non-limiting example, the second period can be 5 seconds, 10 seconds, 15 seconds or more. During this second period, the rotational speed of the substrate can be accelerated. The second predetermined average vertical distance is relatively close to the substrate so that the shortest vertical distance is about 2 mm. The predetermined average vertical distance is then increased to a third predetermined vertical distance for a third period while the substrate is rotating on the substrate holder. This third period can be substantially longer than the second period. 2, 3 or more times longer. The third predetermined average vertical direction distance can make the shortest distance to the substrate longer. For example, around 10 or 15 mm. As the substrate facing surface is raised higher above the substrate, it may be possible to keep the flow below the turbulent threshold by implementing a corresponding decrease in the rotation speed of the substrate. The spin during this third period can continue until drying is complete or the wafer can be moved to the hot plate. Thus, the top surface or cover can be lowered at a point that avoids splashes and avoids turbulence effects early. The top surface or cover is raised to maintain film uniformity. The times and distances provided herein are exemplary, and the actual duration, rotational speed, distance may depend on the given chemical and / or recipe process being used.

  In other embodiments, the substrate facing surface has an outer ring-shaped section and an inner ring-shaped section. The inner ring-shaped section is closer to the axis of rotation than the outer ring-shaped section. The inner ring-shaped section of the substrate facing surface has a first radius of curvature, and the outer ring-shaped section of the substrate facing surface has a second radius of curvature. The second radius of curvature is different from the first radius of curvature. As shown in FIG. 3, the substrate facing surface is convex with respect to the workpiece surface. The first radius of curvature can be between about 20 and 90 millimeters, while the second radius of curvature can be between about 1000 and 2000 millimeters. Alternatively, the first radius of curvature can be between about 50 millimeters and 70 millimeters, while the second radius of curvature can be between about 1300 millimeters and 1500 millimeters.

  In some embodiments, the substrate facing surface is convex with respect to the work surface such that the distance between the substrate facing surface and the work surface decreases in the radial direction toward the outer edge of the work surface. , Defining the shape of a cone with the top cut in a plane. While the substrate facing surface is curved, the fluid flow member itself can be a relatively flat, like a plate, or a block having a large thickness. The substrate facing surface can have a bend selected to improve drying uniformity during the spin coating process. That is, a shape having a specific bending condition can be selected to improve drying uniformity when the substrate is dried by spinning. A varying given vertical distance between the substrate facing surface and the workpiece surface can be selected to minimize turbulence on the workpiece surface. Note that if the height is relatively large (eg, greater than 10 centimeters, etc.), there may be little gain. Similarly, there may be some turbulence and / or uniformity degradation if the height is too small (probably less than 1 millimeter). Therefore, the degree of bending is optimized for uniformity and the height is chosen to balance uniformity and turbulence.

  FIG. 4 shows an enlarged cross-sectional view of an example fluid flow member similar to FIG. The fluid flow member of FIG. 4 has a generally radial bend, but as shown in the cross-sectional view, the substrate facing surface 155 includes a plurality of planar (linear) segments. Thus, the plurality of planar radial segments are such that the fluid flow member has a cross-sectional curvature that includes a plurality of linear segments, such that the substrate facing surface of the fluid flow member can be shown as part of the substrate facing surface 155. Can be included.

  In other embodiments, the substrate facing surface can be configured to rotate with the substrate holder as shown in FIG. Depending on the particular material and processing conditions, uniformity and fluid flow gain can be obtained with a fluid flow member that rotates in synchrony with the substrate.

  FIG. 6 is a top view of various configurations of the fluid flow member. In these embodiments, the fluid flow member defines an opening such that the fluid flow member forms a partial ring above the substrate holder. According to a non-limiting embodiment, FIG. 6A shows a fluid flow member that defines an angular opening. FIG. 6B shows a fluid flow member that is essentially a semicircle. FIG. 6C shows an example of openings where the line edges of the openings are generally perpendicular to each other.

  FIG. 7 shows a top view of a segmented fluid flow member or top plate. In this embodiment, the fluid flow member includes a plurality of sections that can be mechanically moved (vertically or horizontally) from the substrate holder. Such movement can be beneficial not only to allow movement of the nozzle arm, but also to allow placement and removal of the substrate on the substrate holder. In one embodiment, each section of the fluid flow member can be attached to a movable arm so that no part of the fluid flow member covers the wafer. Each arm can move in synchrony with the other arm to form a continuous fluid flow member. The sections can also be moved away at relatively short distances to better optimize the balance between thickness uniformity and turbulence control. Thus, one embodiment includes a fluid flow member that includes two or more segments (eg, four segments) such that at least one segment is configured to move away from an adjacent segment. Note that such segments can be substantially flat segments having a radial bend as described above, or generally forming a flat substrate-facing surface.

  8 to 11 are diagrams for explaining a fluid flow member that dynamically changes the central opening. 8A and 8B are top views of a fluid flow member having an opening with a given diameter, where the given diameter increases to reduce the total area of the fluid flow member. Show. FIG. 9 is a top view of one example embodiment of such a fluid flow member defining a generally circular opening about the axis of rotation (of the substrate holder / wafer), and FIG. 10 shows a side view. The fluid flow member is configured such that the diameter of its defined opening can be increased and / or decreased. The examples shown incorporate techniques such as diaphragms or shutter type apertures in nature.

  The fluid flow member can include a diaphragm member and a ring-shaped base plate 162. The diaphragm member can include a plurality of components, such as a blade 164 and a rod 166. The rod 166 passes through the slot 165 of the blade 164 and holds the blade via the fixture 167. The rod 166 can also be attached to the mounting ring 168. Movement of the mounting ring 168 causes the blade to increase and / or decrease the diameter of the defined opening by rotation of the mounting ring. As the mounting ring 168 rotates, the rod 166 can move through the slot 165, thereby changing its position, such as by sliding the blades 164 against each other. This in turn increases or decreases the defined opening. Thus, in this embodiment, the fluid flow member can be viewed as a ring having an adjustable inner radius or diameter. Such adjustment capability allows the fluid flow member to be dynamically adjusted for specific applications.

  Other embodiments include a method of manufacturing a semiconductor device. This method includes a plurality of steps. The substrate is positioned on the substrate holder, such as by using a robot arm. The substrate holder holds the substrate in the horizontal direction. The substrate holder has a rotation axis. The substrate has a bottom surface that contacts the substrate holder, and has a work surface opposite to the bottom surface. The fluid flow member is positioned above the substrate holder. The fluid flow member has a substrate facing surface such that positioning the fluid flow member includes positioning the substrate facing surface above the work surface in the vertical direction at a predetermined average vertical distance above the work surface. At least a portion of the substrate facing surface is bent such that a given vertical distance between the substrate facing surface and the workpiece surface changes radially relative to a given radial distance from the axis of rotation. . A liquid material such as a resist is dispensed onto the work surface of the substrate via a liquid dispenser positioned above the substrate. The substrate and substrate holder are then spun through a rotating mechanism coupled to the substrate holder so that the liquid material spreads across the work surface of the substrate.

  In another embodiment, the substrate facing surface is maintained at a predetermined average vertical distance above the work surface before dispensing the liquid material on the work surface. Subsequent to initiating dispensing of the liquid material, the predetermined average vertical distance is reduced to a second predetermined average vertical distance via a vertical movement mechanism. The substrate facing surface has an outer ring-shaped section and an inner ring-shaped section, and the inner ring-shaped section is closer to the rotation axis than the outer ring-shaped section. While the inner ring shape of the substrate facing surface is bent in the radial direction, the outer ring shape of the substrate facing surface has a linear slope in the generally radial direction. Thereby, by reducing the predetermined average vertical distance to the second predetermined vertical distance, the outer section of the substrate facing surface is positioned at a position less than about 4 mm from the work surface. The outer section extends beyond a radial distance 127 of about 80-120 millimeters from the axis of rotation. The outer section extends beyond a radial distance 127 of about 100-170 millimeters from the axis of rotation when the work surface has a diameter of approximately 450 millimeters.

  It should be noted that there are several variables that can affect the maximum angular velocity using a fluid flow member. For example, optimal pressure helps to promote laminar flow. If the pressure is too low, backflow conditions can cause turbulence. Other variables include the type of substrate and the type of liquid material. The wafer is not required to have such a shape, but is typically circular or disk-shaped, and the spin apparatus can function with other shapes of rectangles and substrates. There are many different types of resists and solvents that can be selected. Each solvent can have flow and evaporation characteristics, respectively. Therefore, it should be understood that based on the substrate and resist characteristics, the fluid flow member, average height, and rotational speed can be adjusted to produce optimum dry time film uniformity. For example, for resists commonly used for resists on wafers in semiconductor manufacturing, the relatively large section of the outer diameter has a vertical distance between the work surface and the substrate facing surface of less than about 3 millimeters. Is advantageous. According to a non-limiting example, when processing a wafer having a radius of 150 mm, the vertical distance above about 110 mm (about 165 mm for a wafer having a radius of 225 mm) is less than about 3 millimeters, and When set to about 1.5 mm, this results in a dramatically improved laminar flow for larger rotational speeds, such as up to 2800 rpm or higher.

  Another embodiment includes reducing the first predetermined average vertical distance to a second predetermined average vertical distance within a predetermined time after initiating dispensing of the liquid material onto the work surface. According to a non-limiting embodiment, the resist is dispensed onto the substrate, the substrate spins, and after about 1 second, the resist covers the substrate to facilitate laminar flow during spin drying. Can be lowered. In another embodiment, the substrate facing surface can be rotated in the same rotational direction as the substrate holder such that the substrate facing surface rotates at substantially the same angular velocity as the workpiece surface.

  Other embodiments include a method of changing the cup exhaust in various recipe steps to optimize the balance between film thickness uniformity and particle generation while maintaining turbulence control. When the exhaust rate is relatively low, the film thickness uniformity is generally better when the top plate (fluid flow member) is used. That is, a relatively low exhaust rate results in a more uniform film thickness. However, as a conflicting interest, an exhaust rate lower than a predetermined value may result in more particles landing on the wafer being processed. Since this risk is higher for a particular process step, the method can include increasing emissions during a particular process step that is more likely to be contaminated with particles. In addition, if the exhaust is too low, pressure may be applied to the spin coating module, pushing the particles against other parts of the wafer manufacturing system. Therefore, typically a lower exhaust rate results in better uniformity, but typically a higher exhaust rate results in fewer defects. Therefore, the present technology maintains defects lower than a predetermined amount and uniformity higher than a predetermined value by adjusting the exhaust rate in combination with the use of a fluid flow member.

  The fluid flow members and methods herein can improve uniformity to varying degrees depending on processing conditions and liquid material properties. For example, rotating a 300 mm substrate to about 2800-3000 rpm without creating a turbulent effect based on the particular choice of pressure, liquid material type, and technology herein will produce a turbulent effect. Without being able to rotate a 450 mm substrate to about 1200-1400 rpm.

  While only certain embodiments of the present invention have been described above, many modifications will be readily apparent to those skilled in the art without departing substantially from the novel teachings and advantages of the present application. I understand that. Accordingly, all such modifications are intended to be included within the scope of this invention.

Claims (27)

A spin coating apparatus for coating a substrate, the spin coating apparatus comprising:
A substrate holder configured to hold the substrate in a horizontal direction during a spin coating process;
A rotation mechanism connected to the substrate holder and configured to rotate the substrate holder about a rotation axis;
A liquid dispenser configured to dispense liquid material onto a work surface of the substrate when the substrate is disposed on the substrate holder, the work surface having a circular shape; A liquid dispenser that is planar and opposite the bottom surface of the substrate that contacts the substrate holder;
A ring-shaped fluid flow member having a substrate facing surface, the fluid flow member being vertically above a ring-shaped portion of the work surface of the substrate when the substrate is disposed on the substrate holder. said substrate-facing surface is configured to be positioned so that is positioned, the ring-shaped portion of the workpiece surface extends from the outer edge of the work surface to a predetermined radial distance from said rotary shaft, said substrate-facing surface A fluid flow member bent such that a given vertical distance between the substrate facing surface and the workpiece surface varies radially relative to a given radial distance from the rotational axis ;
The average vertical direction between the substrate facing surface and the workpiece surface when the substrate is disposed on the substrate holder and while the rotation mechanism operates to rotate the substrate holder A vertical movement mechanism configured to increase or decrease the distance, and
The substrate facing surface has an outer ring shaped section and an inner ring shaped section, the inner ring shaped section being closer to the axis of rotation than the outer ring shaped section, the inner ring shaped section of the substrate facing surface Is above the inner portion of the ring-shaped portion of the work surface and has a first radius of curvature, and the outer ring-shaped section of the substrate facing surface is above the edge portion of the ring-shaped portion of the work surface. The spin coating apparatus has a second radius of curvature, the second radius of curvature is different from the first radius of curvature, and the substrate facing surface is convex with respect to the work surface.
Spin coating equipment.   The given vertical distance between the substrate facing surface and the work surface changes such that the given vertical distance becomes shorter as the radial distance from the rotation axis becomes longer. Item 4. The spin coating apparatus according to Item 1.   The spin coating apparatus according to claim 1, wherein the fluid flow member defines a circular opening vertically above a circular portion of the work surface, and the circular opening extends from the rotating shaft to the predetermined radial distance. . The first radius of curvature is between about 20 millimeters and 90 millimeters;
The spin coating apparatus of claim 1, wherein the second radius of curvature is between about 1000 millimeters and 2000 millimeters. The first radius of curvature is between about 50 millimeters and 70 millimeters;
The spin coating apparatus of claim 4, wherein the second radius of curvature is between about 1300 millimeters and 1500 millimeters.   The substrate facing surface has a flat top portion that is convex with respect to the work surface so that a distance between the substrate facing surface and the work surface decreases in a radial direction toward an outer edge of the work surface. The spin coating apparatus according to claim 1, wherein the spin coating apparatus defines a shape of a cut cone.   The spin coating apparatus according to claim 6, wherein the substrate facing surface has a curvature selected to improve drying uniformity during a spin coating process.   The spin coating apparatus according to claim 7, wherein a given given vertical distance between the substrate facing surface and the work surface is selected to minimize turbulence on the work surface.   The spin coating apparatus of claim 1, wherein the fluid flow member includes two or more segments configured to move at least one segment away from an adjacent segment.   The spin coating apparatus of claim 9, wherein the fluid flow member includes four segments, each segment configured to move away from an adjacent segment.   The spin coating apparatus according to claim 1, wherein the substrate facing surface of the fluid flow member includes a plurality of planar radial segments such that the fluid flow member has a cross-sectional curvature including a plurality of linear segments. It said fluid flow member, said fluid flow member defines an opening so as to form a partial ring above the substrate, spin coating apparatus according to claim 1. A method of manufacturing a semiconductor device, the method comprising:
A step of positioning the substrate on the substrate holder, wherein the substrate holder holds the substrate in a horizontal direction and has a rotation axis, and the substrate has a bottom surface contacting the substrate holder, and the bottom surface A process having a work surface on the opposite side;
Positioning the fluid flow member above the substrate holder , the fluid flow member including a substrate facing surface, the positioning the fluid flow member at a predetermined average vertical distance above the workpiece surface; Positioning the substrate facing surface vertically above the work surface, wherein at least a portion of the substrate facing surface has a given vertical distance between the substrate facing surface and the work surface. Bending to change radially for a given radial distance from the axis of rotation;
A step of dispensing a liquid material onto a work surface of the substrate through a liquid dispenser positioned above the substrate,
Spinning the substrate and the substrate holder via a rotation mechanism coupled to the substrate holder so that the liquid material spreads across the work surface of the substrate;
Maintaining the substrate facing surface at the predetermined average vertical distance above the work surface before the step of dispensing the liquid material onto the work surface;
Following the start of dispensing to the liquid material, reducing the predetermined average vertical distance to a second predetermined average vertical distance via a vertical movement mechanism . The substrate facing surface has an outer ring-shaped section and an inner ring-shaped section, the inner ring-shaped section being closer to the rotational axis than the outer ring-shaped section, and the outer ring-shaped section of the substrate facing surface is While having a substantially linear slope in the radial direction, the inner ring-shaped section of the substrate facing surface is bent in the radial direction;
Wherein the predetermined average vertical distance of the step of shortening the second predetermined average vertical distance, outer section of the substrate opposing surface is positioned from the workpiece surface to less than about 4 mm,
The outer section extends beyond a radial distance of about 80-120 millimeters from the axis of rotation when the work surface has a diameter of about 300 millimeters;
14. The method of claim 13, wherein the outer section extends beyond a radial distance of about 100-170 millimeters from the axis of rotation when the work surface has a diameter of about 450 millimeters.   The method according to claim 13, wherein the step of shortening the predetermined average vertical distance to a second predetermined average vertical distance occurs within a predetermined time from the start of dispensing the liquid material onto the workpiece surface. A method of manufacturing a semiconductor device, the method comprising:
A step of positioning the substrate on the substrate holder, wherein the substrate holder holds the substrate in a horizontal direction and has a rotation axis, and the substrate has a bottom surface contacting the substrate holder, and the bottom surface A process having a work surface on the opposite side;
Positioning the fluid flow member above the substrate holder, the fluid flow member including a substrate facing surface, the positioning the fluid flow member at a predetermined average vertical distance above the workpiece surface; Positioning the substrate facing surface vertically above the work surface, wherein at least a portion of the substrate facing surface has a given vertical distance between the substrate facing surface and the work surface. Bending to change radially for a given radial distance from the axis of rotation;
Dispensing a liquid material onto a work surface of the substrate via a liquid dispenser positioned above the substrate;
Spinning the substrate and the substrate holder via a rotation mechanism coupled to the substrate holder so that the liquid material spreads across the work surface of the substrate;
Wherein as the substrate opposing surface is rotated by the workpiece surface and substantially the same angular velocity, the method comprising the steps of rotating the substrate opposing surface in the same direction of rotation and the substrate holder. Process, by combining a plurality of fluid flow member segments mechanically to form said fluid flow member, The method according to claim 13 for positioning said fluid flow member above the substrate holder. A method of manufacturing a semiconductor device, the method comprising:
A step of positioning the substrate on the substrate holder, wherein the substrate holder holds the substrate in a horizontal direction and has a rotation axis, and the substrate has a bottom surface contacting the substrate holder, and the bottom surface A process having a work surface on the opposite side;
Positioning the fluid flow member above the substrate holder, the fluid flow member including a substrate facing surface, the positioning the fluid flow member at a predetermined average vertical distance above the workpiece surface; Positioning the substrate facing surface vertically above the work surface, wherein at least a portion of the substrate facing surface has a given vertical distance between the substrate facing surface and the work surface. Bending to change radially for a given radial distance from the axis of rotation;
Dispensing a liquid material onto a work surface of the substrate via a liquid dispenser positioned above the substrate;
Spinning the substrate and the substrate holder via a rotation mechanism coupled to the substrate holder so that the liquid material spreads across the work surface of the substrate;
A step of maintaining the substrate opposing surface in a first period, before the step of dispensing the liquid material on the workpiece surface, the predetermined average vertical distance above the workpiece surface,
Second period, following the start of dispensing to the liquid material, through the vertical movement mechanism, shortening the predetermined average vertical distance to a second predetermined average vertical distance,
Third period, while the substrate continues to spin on serial substrate holder, the method comprising the steps of extending the predetermined average vertical distance to the third predetermined vertical distance. A spin coating apparatus for coating a substrate, the spin coating apparatus comprising:
A substrate holder configured to hold the substrate in a horizontal direction during a spin coating process;
A rotation mechanism connected to the substrate holder and configured to rotate the substrate holder about a rotation axis;
A liquid dispenser configured to dispense a liquid material onto a work surface of the substrate when the substrate is disposed on the substrate holder, the work surface being planar, A liquid dispenser on the opposite side of the bottom surface of the substrate that contacts the substrate holder;
A fluid flow member having a substrate facing surface,
The substrate facing surface is positioned vertically above the work surface of the substrate when the substrate is disposed on the substrate holder, and the fluid flow member is substantially circular about the rotation axis. The fluid flow member is configured to increase or decrease the diameter of the defined opening ;
The fluid flow member includes a diaphragm member and a ring-shaped base plate,
The diaphragm member includes a plurality of blades configured to slide relative to each other to increase or decrease the diameter of the defined opening;
The plurality of blades are attached to the mounting ring via a plurality of rods such that by rotating the mounting ring, the blade increases or decreases the diameter of the defined opening.
Spin coating equipment. A spin coating apparatus for coating a substrate, the spin coating apparatus comprising:
  A substrate holder configured to hold the substrate in a horizontal direction during a spin coating process;
  A rotation mechanism connected to the substrate holder and configured to rotate the substrate holder about a rotation axis;
  A liquid dispenser configured to dispense liquid material onto a work surface of the substrate when the substrate is disposed on the substrate holder, the work surface having a circular shape; A liquid dispenser that is planar and opposite the bottom surface of the substrate that contacts the substrate holder;
  A ring-shaped fluid flow member having a substrate facing surface, the fluid flow member being vertically above a ring-shaped portion of the work surface of the substrate when the substrate is disposed on the substrate holder. The substrate facing surface is positioned so as to be positioned, and a ring-shaped portion of the work surface extends from an outer edge of the work surface to a predetermined radial distance from the rotation shaft, A fluid flow that is curved such that a given vertical distance between the substrate facing surface and the workpiece surface varies radially relative to a given radial distance from the axis of rotation. Members,
  The average vertical direction between the substrate facing surface and the workpiece surface when the substrate is disposed on the substrate holder and while the rotation mechanism operates to rotate the substrate holder A vertical movement mechanism configured to increase or decrease the distance, and
  The substrate facing surface has a linear outer ring-shaped section and a bent inner ring-shaped section, the bent inner ring-shaped section being closer to the axis of rotation than the linear outer ring-shaped section; A curved inner ring-shaped section of the substrate facing surface is above the inner portion of the ring-shaped portion of the work surface and has a radius of curvature, and a linear outer ring-shaped section of the substrate facing surface is formed of the work surface. A spin coating device above the edge of the ring-shaped part. 21. The spin coating apparatus of claim 20, wherein the linear outer ring-shaped section of the substrate facing surface has a linear slope in the radial direction. When the fluid flow member is positioned vertically above the work surface of the substrate, there is a substantially constant vertical distance between the work surface and the linear outer ring-shaped section of the substrate facing surface. 21. The spin coating apparatus of claim 20, wherein the linear outer ring-shaped section is flat. 21. The spin coating apparatus of claim 20, wherein the vertical movement mechanism sets a vertical distance between the outer ring-shaped section and the work surface to less than about 5 millimeters. 23. The spin coating apparatus of claim 22, wherein the radius of curvature of the inner ring-shaped section of the substrate facing surface is between about 20 millimeters and 90 millimeters. The given vertical distance between the substrate facing surface and the work surface changes such that the given vertical distance becomes shorter as the radial distance from the rotation axis becomes longer. Item 20. The spin coating apparatus according to Item 20. The spin coating apparatus according to claim 20, wherein the fluid flow member defines a circular opening vertically above a circular portion of the work surface, and the circular opening extends from the rotating shaft to the predetermined radial distance. . A spin coating apparatus for coating a substrate, the spin coating apparatus comprising:
  A substrate holder configured to hold the substrate in a horizontal direction during a spin coating process;
  A rotation mechanism connected to the substrate holder and configured to rotate the substrate holder about a rotation axis;
  A liquid dispenser configured to dispense a liquid material onto a work surface of the substrate when the substrate is disposed on the substrate holder, the work surface being planar, A liquid dispenser on the opposite side of the bottom surface of the substrate that contacts the substrate holder;
  A fluid flow member having a substrate facing surface,
  The fluid flow member is configured to be positioned so that the substrate facing surface is positioned vertically above the work surface of the substrate when the substrate is disposed on the substrate holder. At least a portion of the facing surface is bent such that a given vertical distance between the substrate facing surface and the workpiece surface changes in a radial direction with respect to a given radial distance from the rotation axis. And
  The spin coating apparatus, wherein the substrate facing surface includes a plurality of planar radial segments such that the fluid flow member has a cross-sectional curvature including a plurality of linear segments.

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