Spin coating apparatus and method for forming a layer on a semiconductor wafer

Abstract

A method and spin coater for forming a layer of uniform thickness on a semiconductor wafer having a central region and an outer edge. The method includes depositing a layer of coating material on the central region of the semiconductor wafer, the layer formed from the coating material; rotating the semiconductor wafer about an axis, the coating material urged to spread from the central region to the outer edge of the semiconductor wafer by centrifugal force; and creating a pressure differential in one or more regions proximate the outer edge of the semiconductor wafer.

Description

Technical Field

[0001] The embodiments of the present invention relate to a semiconductor device and method, and more particularly to a spin coating device and method for forming a layer on a semiconductor wafer. Background Technology

[0002] The following relates to semiconductor technology, particularly methods and apparatus for improving the thickness uniformity of spin coatings during semiconductor manufacturing processes. Summary of the Invention

[0003] According to some embodiments, a method for forming a layer on a semiconductor wafer having a central region and an outer edge includes depositing a coating material on the central region of the semiconductor wafer, the layer being formed by the coating material; rotating the semiconductor wafer about an axis to cause the coating material to extend from the central region to the outer edge of the semiconductor wafer by centrifugal force; and generating a pressure difference in one or more regions near the outer edge of the semiconductor wafer.

[0004] According to some embodiments, a spin coater for forming a layer on a semiconductor wafer having a central region and an outer edge includes a rotatable chuck configured to hold the semiconductor wafer; a nozzle configured to selectively deposit a coating material on the central region of the semiconductor wafer held on the rotatable chuck, the coating material forming the layer, wherein the semiconductor wafer is rotated about an axis by rotation of the rotatable chuck and centrifugal force is generated, causing the coating material to spread from the central region to the outer edge of the semiconductor wafer; a flow field stabilizer; and an airflow generator for generating airflow. The flow field stabilizer includes an annular wall and one or more pin holes. The annular wall is configured such that when the semiconductor wafer is secured to the rotatable chuck, the annular wall approaches and surrounds the outer edge of the semiconductor wafer. The annular wall has an inner surface facing the outer edge of the semiconductor wafer and an outer surface opposite the inner surface. The pin holes extend from the inner surface through the annular wall to the outer surface. Each of the pin holes defines an internal opening at the inner surface of the annular wall and an external opening at the outer surface of the annular wall. At least a portion of the airflow is directed to flow along the outer side of the outer surface of the wall of the flow field stabilizer and through the external opening of the pin hole.

[0005] According to some embodiments, a spin coating apparatus for forming a layer on a semiconductor wafer includes a deposition machine that selectively deposits a coating material on the semiconductor wafer; a suction cup that holds the semiconductor wafer so that the semiconductor wafer rotates together with the suction cup, thereby extending the coating material toward an outer edge of the semiconductor wafer; a wall that is close to and at least partially surrounds the outer edge of the semiconductor wafer; and one or more pin holes that extend through the wall, each of the pin holes defining an internal opening at an inner surface of the wall and an external opening at an outer surface of the wall, wherein a local pressure differential is generated on the pin holes by causing gas to flow along the outer surface of the wall and through the external opening of the pin holes, the local pressure differential being used to draw the coating material toward the outer edge of the semiconductor wafer. Attached Figure Description

[0006] A thorough understanding of the various aspects of this disclosure will be best achieved by reading the following detailed description in conjunction with the accompanying drawings. It should be noted that, in accordance with industry standard practice, the features are not drawn to scale. In fact, the sizes of the features may be arbitrarily increased or decreased for clarity of explanation.

[0007] Figure 1 A cross-sectional view of a spin coater for forming a spin coating on a semiconductor wafer according to some embodiments disclosed herein is shown schematically.

[0008] Figure 2 A partially exploded perspective view of a spin coater for forming a spin coating on a semiconductor wafer according to some embodiments disclosed herein is shown schematically, wherein a portion of selected components has been cut off in the view.

[0009] Figure 3 This is a flowchart illustrating a method and / or process for spin coating on a semiconductor wafer according to some embodiments disclosed herein.

[0010] Figure 4 The illustrations illustrate spin coating equipment for applying coatings to semiconductor wafers according to some embodiments disclosed herein.

[0011] Explanation of icon numbers

[0012] 100: Spin coater;

[0013] 110: Top cup section;

[0014] 114, 124, 134: Side walls;

[0015] 116, 136: Circular lip margin;

[0016] 120: Middle cup section;

[0017] 122: Upper level;

[0018] 130: Base of the cup;

[0019] 132: Lower level;

[0020] 132a: Exhaust port;

[0021] 136a: Entry port;

[0022] 140: Flow field stabilizer;

[0023] 142: Inner surface;

[0024] 144: Outer surface;

[0025] 146: Pin hole;

[0026] 150: Rotatable suction cup;

[0027] 152: Axis;

[0028] 160: Material deposition nozzle;

[0029] 162: Spin coating;

[0030] 170: Airflow generator;

[0031] 180: Gap;

[0032] 190, 192: Arrows;

[0033] 200: Process;

[0034] 210, 220, 230, 240, 250: Steps;

[0035] 300: Spin coating equipment;

[0036] 310: Processor;

[0037] 320: User Interface;

[0038] W: Semiconductor wafer / chip;

[0039] Z: Central vertical axis;

[0040] a1, a2: Dimensions;

[0041] b1, b2: Diameter;

[0042] c: distance;

[0043] d1, d2, d3, d4: radial distances;

[0044] h1: Vertical height;

[0045] h2: Distance;

[0046] t1: Thickness;

[0047] w1: Width;

[0048] α, β: Angles. Detailed Implementation

[0049] The following disclosure provides numerous different embodiments or instances for implementing various features of the provided subject matter. Specific examples of components and arrangements are described below to simplify this disclosure. Of course, these are merely examples and not intended to be limiting. For example, in the following description, forming a first feature on or over a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features such that the first and second features are not in direct contact. Furthermore, reference numerals and / or letters may be reused in various instances of this disclosure. Such reuse is for the sake of brevity and clarity and does not in itself imply a relationship between the various embodiments and / or configurations discussed.

[0050] Furthermore, for ease of explanation, spatially relative terms such as "beneath," "below," "lower," "above," and "upper" may be used herein to describe the relationship between one component or feature shown in the figures and another component or feature. These spatially relative terms are intended to cover different orientations of the device in use or operation, in addition to those shown in the figures. The device may have other orientations (rotated 90 degrees or in other orientations), and the spatially relative descriptions used herein will be interpreted accordingly.

[0051] Generally, semiconductor manufacturing processes involve numerous process steps in which various material layers are stacked one after another and patterned accordingly. Typically, some of these layers (e.g., photoresist layers or polyimide layers) can be formed by a so-called spin coating process, in which a fluid or other flowable material is deposited on top of a central region of a semiconductor wafer. In practice, the semiconductor wafer is suitably spinned or rotated, for example around its central axis, and centrifugal force causes the deposited material to diffuse outward from the initially deposited central region and / or flow to the periphery or edges of the semiconductor wafer. Using conventional spin coating techniques and / or equipment, there is a risk that the thickness of the spin-coated layer may not be substantially uniform in the final thickness; for example, the thickness at or near the periphery or edges of the semiconductor wafer may be slightly thinner than the central region where the deposited material was initially deposited. One advantage of the methods and / or spin coaters disclosed herein is that they promote uniformity in the thickness of the spin-coated layer.

[0052] As is understood herein, the reduced thickness of spin coatings near the wafer edge may be due to higher airflow at the wafer edge. Spin coating tools may employ forced flow of filtered air or other clean airflow sources to reduce the deposition of unwanted particles and / or similar contaminants on the spin coating. Depending on the type of material being deposited, this airflow may additionally or alternatively be used to dissipate toxic fumes. As is understood herein, the airflow in typical spin coating tools tends to be higher at the wafer edge, which results in a reduced thickness of the spin coating near the wafer edge, which in turn reduces device yield in the edge region. This is problematic because the edge region constitutes a large portion of the entire wafer area. The embodiments disclosed herein provide a flow field stabilizer comprising an annular wall surrounding the wafer edge, the annular wall having pin holes designed to divide the airflow into sub-flows on the outer and inner sides of the annular wall, respectively, to utilize Bernoulli's principle to adjust the airflow near the wafer edge, thereby improving the uniformity of the spin coating thickness.

[0053] Figure 1 A cross-sectional illustration of a spin coater or spin coater 100 showing aspects of some suitable embodiments disclosed herein. Figure 2 This illustration shows an exploded perspective view of selected components of a spin coater or spin coater 100 according to some suitable embodiments disclosed herein, wherein portions of the selected components have been cut out in the view to show various structures. In some embodiments, as shown, the spin coater 100 includes: a top cup 110, an intermediate cup 120, a bottom cup 130, a flow field stabilizer 140, a rotatable suction cup 150, a material deposition nozzle 160, and an airflow generator 170.

[0054] In some embodiments, the rotatable chuck 150 may be a vacuum chuck, an electrostatic chuck, or other similar chuck suitable for selectively attaching to and / or holding a semiconductor wafer W on its top. In practice, the rotatable chuck 150 may selectively spin and / or rotate, for example about a central longitudinal axis Z, together with the semiconductor wafer W attached to its top, at a desired speed or revolutions per minute (rpms).

[0055] In some embodiments, the material deposition nozzle 160 may selectively deposit an initial fluid or flowable coating material, such as a photoresist material or a polyimide material, onto the top surface of a semiconductor wafer W held by a rotatable chuck 150. In some suitable embodiments, the coating material may be, for example, a polyimide material, such as C x H y N z O wAlternatively, another polyimide material or a suitable photoresist material may be used. The material deposition nozzle 160 is suitably positioned to initially deposit coating material on the top of the semiconductor wafer W at or near the center or central region of the semiconductor wafer W. As the semiconductor wafer W rotates, for example, with or / or spins together with the rotatable chuck 150 holding the semiconductor wafer W, the deposited flowable coating material is dispersed and / or flows outward from the central region of the semiconductor wafer W toward the periphery or edge of the semiconductor wafer W under centrifugal force, thereby forming a spin coating 162 on the semiconductor wafer W. In some suitable embodiments, the initial fluid or flowable coating material used to form the spin coating 162 has a relatively high viscosity. For example, the coating material used to form the spin coating 162 may have a viscosity greater than 100 centipoise (cP).

[0056] One potential hazard during the spin coating process is that dust, debris, and / or other undesirable particles may fall or settle on the semiconductor wafer W during the formation of the spin coating layer 162. This fall or settlement of dust, debris, and / or other undesirable particles on the semiconductor wafer W and / or the spin coating layer 162 formed thereon can potentially damage or harm sensitive components of the semiconductor being manufactured, and may cause malfunctions or defects. Therefore, in some suitable embodiments, an airflow generator 170 generates an airflow during the spin coating process performed with the spin coater 100. For example, in some suitable embodiments, the airflow generator 170 may be a fan, etc. In some suitable embodiments, the gas used to generate the airflow by the airflow generator 170 may be substantially clean (e.g., substantially free of dust, debris, and / or other particulate contaminants) and / or filtered air with suitable temperature and / or humidity control. In some embodiments, another suitable gas or a suitable combination of gases may be used. One advantage of the generated airflow is that it helps prevent unwanted particles and / or similar contaminants from falling or settling on the forming swirl coating 162, which could potentially damage or harm sensitive components of the semiconductor wafer W or otherwise cause malfunctions or defects. The illustrated airflow generator 170 is a fan that pushes airflow downwards onto the top surface of the wafer W. However, the airflow generator can be embodied in other ways, such as a fan positioned below the wafer W to pull the airflow, or as ducts and exhaust hoods that deliver pressurized gas from gas cylinders, pressurized laboratory gas supplies, etc., to the wafer W. The airflow generator may optionally include high-efficiency particulate absorbing (HEPA) filters, etc., to remove gas-borne particles from the airflow.

[0057] In some suitable embodiments, the top cup 110, the middle cup 120, the bottom cup 130, and the flow field stabilizer 140 cooperate to regulate and / or guide the airflow generated by the airflow generator 170. Furthermore, the flow field stabilizer 140 and / or the aforementioned arrangement and operation and / or cooperation regulate and / or guide the airflow in a manner that advantageously promotes the uniformity of the thickness of the swirl coating 162.

[0058] In some suitable embodiments, the bottom cup portion 130 forms a chamber in which the rotatable suction cup 150 is centered and / or otherwise accommodated. As shown, the bottom cup portion 130 suitably has: a base or lower layer 132; sidewalls 134, for example, preferably vertical and cylindrical, extending upward from the outer edge or periphery of the base or lower layer 132; and an upper flange or annular lip 136 extending inward from the top of the sidewalls 134 toward the central longitudinal axis Z.

[0059] As shown, the base or lower layer 132 of the bottom cup portion 130 has a central opening through which the shaft 152 of the rotatable suction cup 150 passes. In some embodiments, an exhaust port 132a may be formed in the base or lower layer 132 of the bottom cup portion 130 to allow generated airflow to exit the bottom cup portion 130. In some embodiments, the exhaust port 132a is suitably positioned or located at a radial distance d1 from the central axis Z. Optionally, the exhaust port 132a may include an annular gap or other similar opening formed in the base or lower layer 132 of the bottom cup portion 130. In some suitable embodiments, the exhaust port 132a may include one or more individual or different openings, etc., formed in the base or lower layer 132 of the bottom cup portion 130.

[0060] As shown in the figure, the upper flange or annular lip 136 of the bottom cup portion 130 extends inwardly toward the central Z-axis from the sidewall 134 of the bottom cup portion 130 at an angle α. In some suitable embodiments, the angle α is greater than 90 degrees and less than 180 degrees. In some embodiments, an inlet port 136a may be formed in the upper flange or annular lip 136 to allow the generated airflow to enter the bottom cup portion 130. In some embodiments, the inlet port 136a is suitably located or positioned at a radial distance d2 from the central axis Z. Suitably, as shown in the figure, d2 is greater than d1. Optionally, the inlet port 136a may include an annular gap or other similar opening formed in the upper flange or annular lip 136 of the bottom cup portion 130. In some suitable embodiments, the inlet port 136a may include one or more separate or different openings formed in the upper flange or annular lip 136 of the bottom cup portion 130. Appropriately, as shown in the figure, the inlet port 136a is closer to or closer to the side wall 134 of the bottom cup portion 130, rather than closer to or closer to the inner edge or periphery of the upper flange or annular lip 136.

[0061] In some suitable embodiments, the intermediate cup portion 120 is located and / or accommodated within a cavity defined by the bottom cup portion 130. As shown, the intermediate cup portion 120 suitably has: a top plate or upper layer 122; and side walls 124, which are suitably vertical and cylindrical, and extend downward from the outer edge or periphery of the top plate or upper layer 122. As shown, the top plate or upper layer 122 of the intermediate cup portion 120 also has a central opening through which the shaft 152 of the rotatable suction cup 150 can pass. In some embodiments, the side walls 124 of the intermediate cup portion 120 are suitably located or positioned at a radial distance d3 from the central axis Z. Suitably, as shown, d3 is greater than d1 and less than d2.

[0062] In practice, the sidewall 124 in the intermediate cup portion 120 and the sidewall 134 in the bottom cup portion 130 together form and / or define an annular channel therebetween, through which airflow is guided. That is, the airflow generated by the airflow generator 170 enters the bottom cup portion 130 through the inlet port 136a, then flows between the sidewall 124 of the intermediate cup portion 120 and the sidewall 134 of the bottom cup portion 130, and then exits the bottom cup portion 130 through the exhaust port 132a.

[0063] In some suitable embodiments, the top cup portion 110 is located on and / or sits on the bottom cup portion 130. As shown, the top cup portion 110 suitably has: a sidewall 114, which is suitably vertical and cylindrical, and extends upward from the top of the sidewall 134 of the bottom cup portion 130; and an upper flange or annular lip 116 extending inward from the top of the sidewall 114 toward the central longitudinal axis Z. As shown, the upper flange or annular lip 116 of the top cup portion 110 extends inward from the sidewall 114 of the top cup portion 110 toward the central axis Z at an angle β. In some suitable embodiments, the angle β is approximately 90 degrees. Suitably, the upper flange or annular lip 116 of the top cup portion 110 extends radially inward from the top of the sidewall 114 of the top cup portion 110 by an amount greater than or equal to about 5 mm and less than or equal to about 95 mm. In some suitable embodiments, the upper flange or annular lip 116 of the top cup portion 110 extends inward toward the central axis Z beyond the position of the inlet port 136a formed in the upper flange or annular lip 136 of the bottom cup portion 130. That is, the radial distance d4 from the central axis Z to the inner edge or periphery of the upper flange or annular lip 116 is less than d2.

[0064] As shown in the figure, in some suitable embodiments, the flow field stabilizer 140 is positioned and / or located at the inner edge of the upper flange or annular lip 136 of the bottom cup portion 130. The flow field stabilizer 140 suitably takes the form of annular or cylindrical walls having a first inner surface 142, a second outer surface 144, a thickness t1, and a vertical height h1. In some suitable embodiments, the vertical height h1 of the walls of the flow field stabilizer 140 is in the range of greater than or equal to about 5 mm and less than or equal to about 50 mm. In practice, the inner diameter of the flow field stabilizer 140 is, for example, greater than about 300 mm. In some suitable embodiments, the dimensions of the spin coater 100 and / or its various components or parts are suitably determined to receive and / or accommodate semiconductor wafers W having a diameter up to about 300 mm. The annular wall of the flow field stabilizer partially surrounds the annular edge of the wafer W, and in some embodiments, the annular wall of the flow field stabilizer completely surrounds the annular edge of the wafer W.

[0065] In some suitable embodiments, the wall of the flow field stabilizer 140 is penetrated by a plurality of pin holes 146 extending radially, for example, when viewed from the central axis Z. In some suitable embodiments, the plurality of pin holes 146 extend from the inner surface 142 of the wall through the outer surface 144 of the wall and are approximately equidistant from each other, for example, around the circumference of the flow field stabilizer 140. In some suitable embodiments, the pin holes 146 are spaced apart from each other by a distance c greater than or equal to about 1 mm. These are merely illustrative dimensional ranges; more generally, the size and distribution of the pin holes can be optimized using numerical airflow modeling, etc., to provide the desired control of airflow above the wafer edge according to Bernoulli's principle, in order to optimize the spin coating thickness uniformity from the wafer center to the wafer edge.

[0066] Suitablely, each pin hole 146 is generally shaped like a truncated cone or a right-angled, oblique cone, or other truncated cone or pyramid with a polygonal base, etc. In some suitable embodiments, the geometric area defined by each pin hole 146 at the inner surface 142 of the wall of the flow field stabilizer 140 is smaller than the geometric area defined by the pin hole 146 at the outer surface 144 of the wall of the flow field stabilizer 140. That is, the pin hole 146 flares outward as it extends from the inner surface 142 to the outer surface 144 of the wall of the flow field stabilizer 140. Although the flare of the pin hole shown is linear, in other embodiments, the flare may have some curvature, that is, the pin hole diameter may increase non-linearly from the small diameter of the inner surface 142 to the outer surface 144.

[0067] For example, in some suitable embodiments, the pin hole 146 may have a truncated conical shape, wherein the pin hole 146 has a generally circular geometric region of diameter b1 at the inner surface 142 of the wall of the flow field stabilizer 140 and a generally circular geometric region of diameter b2 at the outer surface 144 of the wall of the flow field stabilizer 140, wherein b1 is smaller than b2. In some suitable embodiments, b1 may be in the range between greater than or equal to about 1 mm and less than or equal to about 50 mm, while still being smaller than b2. In some suitable embodiments, b2 may be in the range between greater than or equal to about 1 mm and less than or equal to about 50 mm, while still being larger than b1. Again, these are merely illustrative dimensional ranges, and more generally, the dimensions can be optimized using numerical airflow modeling, etc.

[0068] In some suitable embodiments, the pin hole 146 may take the shape of a pyramid with a polygonal base, such as, but not limited to, a square or rectangular base. For example, when the pin hole 146 is a pyramid with a square base, the pin hole 146 may have a generally square geometric area of ​​size a1 at the inner surface 142 of the wall of the flow field stabilizer 140 and a generally square geometric area of ​​size a2 at the outer surface 144 of the wall of the flow field stabilizer 140, where a1 is smaller than a2. Similarly, for example, when the pin hole 146 has the shape of a frustum pyramid with a rectangular base, the pin hole 146 may have a generally rectangular geometric area of ​​size a1 at the inner surface 142 of the wall of the flow field stabilizer 140 and a generally rectangular geometric area of ​​size a2 at the outer surface 144 of the wall of the flow field stabilizer 140, where a1 is smaller than a2.

[0069] In some suitable embodiments, the flow field stabilizer 140 and the top cup portion 110 are sized and / or arranged such that a gap is defined between the outer surface 144 of the wall of the flow field stabilizer 140 and the inner edge or periphery of the upper flange or annular lip 116 of the top cup portion 110. In some suitable embodiments, the gap has a width w1, for example, greater than or equal to about 5 mm measured radially relative to the central axis Z.

[0070] In some suitable embodiments, as shown, the top of the wall of the flow stabilizer 140 rises to and / or extends beyond (i.e., in the Z-axis direction) the upper flange or annular lip 116 of the top cup portion 110. For example, the top of the wall of the flow stabilizer 140 suitably rises above the upper flange or annular lip 116 of the top cup portion 110 and / or extends beyond a distance h2 measured in the Z-axis direction, wherein h2 is in the range of greater than or equal to about 5 mm and less than or equal to about 50 mm.

[0071] As shown in the figure, the upper flange or annular lip 116 of the flow field stabilizer 140 and the top cup portion 110 together form and / or define an annular gap 180, through which airflow is guided. That is, the airflow generated by the airflow generator 170 enters the top cup portion 110 through the gap 180, then flows out of the top cup portion 110 and flows into the bottom cup portion 130 through the inlet port 136a formed in the upper flange or annular lip 136 of the bottom cup portion 130, then flows between the sidewall 124 of the intermediate cup portion 120 and the sidewall 134 of the bottom cup portion 130, and then exits the bottom cup portion 130 through the exhaust port 132a. In some suitable embodiments, most of the airflow generated by the airflow generator 170 (by...) Figure 1 Arrows 190 and 192 in the diagram indicate that the airflow generated by the airflow generator 170 is guided through the gap 180. For example, the airflow generated by the airflow generator 170 is guided through the gap 180 in a range greater than about 50% and less than or equal to about 90%.

[0072] Appropriately, in practice, the flow field stabilizer 140 and / or the pin hole 146 formed therein operate according to the Bernoulli principle and / or utilize the Bernoulli principle to control the airflow above the wafer edge to help promote the uniformity of the thickness of the formed spin coating 162. Furthermore, compared to the inner surface 142 sidewall of the pin hole 146, the relatively large airflow through the gap 180 and flowing through the outer surface 144 sidewall of the flow field stabilizer 140 tends to create small local vacuums or relatively low pressure regions on its outer surface 144 sidewall. The resulting pressure difference tends to generate outward lateral or radial (i.e., from the perspective of the central axis Z) tension, pressure difference, and / or airflow (or more generally, gas flow) through the pin hole 146. Such outward lateral or radial pulling, pressure difference, and / or airflow approaching and / or near the outer edge and / or periphery of the semiconductor wafer W on which the spin coating 162 is applied tends to promote thickness uniformity by increasing the traction, flow, and / or expansion of the coating material toward the outer edge or periphery of the semiconductor wafer W, thereby preventing a relatively thin spin coating 162 near the outer edge or periphery of the semiconductor wafer, for example, compared to a more central region in the semiconductor wafer W where the coating material was initially deposited.

[0073] Figure 3 A flowchart illustrating an exemplary method and / or process 200 for forming a spin coating (e.g., layer 162) on a semiconductor wafer (e.g., semiconductor wafer W) is shown. In a suitable embodiment, the method or process 200 may use previously referenced... Figure 1 and Figure 2 The spin coating tool or spin coater 100 described herein shall be used to perform the coating.

[0074] like Figure 3As shown, the spin coating method or process 200 begins at step 210, in which a semiconductor wafer W is loaded into the spin coater 100. In practice, this loading step 210 appropriately includes securing the semiconductor wafer W onto a rotatable chuck 150.

[0075] In step 220, the airflow may be initiated, generated, and / or otherwise produced, for example, by airflow generator 170. As previously described, in some suitable embodiments, a majority (e.g., greater than 50% and less than or equal to 90%) of the generated airflow is directed through gap 180 and along the outer surface 144 of the wall of flow field stabilizer 140 through pin hole 146, thereby creating a pressure difference between the side of pin hole 146 at the inner surface 142 of the wall of flow field stabilizer 140 and the side of pin hole 146 at the outer surface 144 of the wall of flow field stabilizer 140, according to Bernoulli's principle.

[0076] At step 230, a portion of the fluid or flowable coating material forming layer 162 is deposited onto the loaded semiconductor wafer W, for example, via material deposition nozzle 160, at or near the center or central region of the semiconductor wafer W. In some suitable embodiments, the semiconductor wafer W may be substantially stationary during the initial deposition of the coating material. In some suitable embodiments, the semiconductor wafer W may already be rotating when the coating material is initially deposited, for example, along with the rotation of the rotatable chuck 150, although at a relatively low speed. Once the desired portion of the coating material has been deposited, the material deposition nozzle 160 stops or ceases depositing further material.

[0077] At step 240, the semiconductor wafer W, to which the deposited coating material is attached, is rotated, for example, about a central axis Z, by appropriate rotation of a rotatable chuck 150 on which the semiconductor wafer W is fixed. In some suitable embodiments, the semiconductor wafer W rotates at a relatively higher speed than it may have rotated when the coating material was initially deposited. Therefore, the centrifugal force generated by the rotation of the semiconductor wafer W causes the deposited coating material to diffuse and / or flow across the top surface of the semiconductor wafer W, toward the outer edge or periphery of the semiconductor wafer W. In variant embodiments, the chuck rotation step 240 may be initiated before the coating material deposition in step 230, such that the wafer rotates at a target rpm rate before the deposition step 230 begins.

[0078] It is noteworthy that the flow field stabilizer 140 (e.g., in conjunction with the airflow generated by the airflow generator 170) generates a lateral or radial (i.e., from the perspective of the central axis Z) suction, pressure differential, and / or airflow (or more generally, gas flow) outward through the pin hole 146. This outward lateral or radial suction, pressure differential, and / or airflow, approaching and / or near the outer edge and / or periphery of the semiconductor wafer W on which the spin coating 162 is formed, tends to promote thickness uniformity, for example by increasing the traction force, causing the coating material to flow and / or diffuse toward the outer edge or periphery of the semiconductor wafer W, thereby preventing the spin coating 162 from having a relatively thin dimension near the outer edge or periphery of the semiconductor wafer W, for example, compared to the more central region of the semiconductor wafer W on which the coating material was initially deposited.

[0079] In step 250, when the desired thickness of the spin coating 162 is reached, the rotation of the semiconductor wafer W is stopped, for example by stopping the rotation of the rotatable chuck 150, and after any optional additional drying time has elapsed, the semiconductor wafer W on which the spin coating 162 is formed can be removed from the rotatable chuck 150 and / or otherwise removed from the spin coater 100. More generally, the rotation speed and rotation time can be optimized in a calibration run to achieve optimal thickness uniformity using the flow field stabilizer 140.

[0080] Figure 4This is a schematic illustration of a system or spin coating apparatus 300, including, for example, a spin coater 100. As shown, the apparatus includes a controller or processor 310 that adjusts and / or controls various parts and / or components of the spin coater 100. For example, but not limited to, the controller or processor 310 may: selectively engage or disengage a rotatable chuck 150 to selectively hold or release a semiconductor wafer W placed thereon; selectively rotate or stop the rotatable chuck 150 and / or adjust the rotational speed of the rotatable chuck 150; selectively turn on and / or stop an airflow generator 170 and / or adjust the amount and / or speed of the airflow thereby generated; and selectively adjust a material deposition nozzle 160 to output and / or stop outputting coating material from it. In some suitable embodiments, the controller or processor 310 is coded or otherwise provided to enable the spin coater 100 to automatically perform the spin coating method or process 200. In some suitable embodiments, various parameters or processes 200 for performing the spin coating method, such as, but not limited to, the amount of coating material initially deposited, the rotational speed of the rotatable suction cup 150 at different times, the specification of selectable drying times, and the opening or engagement and / or closing or disengagement when different parts or components of the spin coater 100 are to be rotated, may be pre-coded or otherwise provided to the controller or processor 310. In some suitable embodiments, the spin coating apparatus 300 also includes a user interface 320, including one or more input and / or output devices, such as a keyboard, a display, etc., which a user may selectively use to encode and / or control the operation of the spin coater 100 and to receive information about the operating status of the spin coater 100 and / or its respective parts and / or components.

[0081] In some embodiments, the controller or processor 310 may be implemented by a combination of hardware and software or firmware, or a combination thereof. Specifically, one or more controllers may be processors, circuits, computers, and / or configured and / or otherwise provided to perform tasks, steps, processes, methods, and / or functions described herein. For example, a microprocessor, microcontroller, computer, server, or other electronic data processing device embodying a controller may be provided, supplied, and / or encoded with a suitable list of codes (e.g., source code, interpreter code, object code, directly executable code, etc.) or other similar instructions or software or firmware such that, when run and / or executed by a computer or other electronic data processing device, one or more of the tasks, steps, processes, methods, and / or functions described herein are performed or otherwise carried out. Properly, the list of codes or other similar instructions or software or firmware is implemented and / or recorded, stored, covered, or included on and / or on a non-transitory computer and / or machine-readable storage medium or medium so that it may be provided to and / or executed by a computer or other electronic data processing device. For example, suitable storage media and / or media may include, but are not limited to: floppy disks, flexible disks, hard disks, magnetic tapes or any other magnetic storage media or media, CD-ROMs, DVDs, optical discs or any other optical media or media, RAM, ROMs, PROMs, EPROMs, FLASH-EPROMs, or other memory or chips or cassette tapes, or any other tangible media or media that can be read and used by a computer or machine or electronic data processing device. Essentially, as used herein, non-transitory computer-readable and / or machine-readable media and / or media include all computer-readable and / or machine-readable media and / or media other than transiently propagating signals.

[0082] Generally, any one or more specific tasks, steps, processes, methods, functions, components, and / or building blocks described herein can be implemented in or on one or more general-purpose computers, special-purpose computers, and / or embodiments, such as programmed microprocessors or microcontrollers and peripheral integrated circuit components, ASICs or other integrated circuits, digital signal processors, hardwired electronic or logic circuits, such as distributed component circuits, programmable logic devices, such as PLDs, PLAs, FPGAs, graphics adapters, CPUs (GPUs), or PALs. Generally, any device capable of implementing a finite state machine can be used, which in turn can implement the corresponding tasks, steps, processes, methods, and / or functions described herein.

[0083] The following describes some further illustrative embodiments.

[0084] In some embodiments, a method is provided for forming a layer on a semiconductor wafer having a central region and an outer edge. The method includes: depositing a coating material on the central region of the semiconductor wafer, the layer being formed by the coating material; rotating the semiconductor wafer about an axis to cause the coating material to extend from the central region to the outer edge of the semiconductor wafer by centrifugal force; and generating a pressure difference in one or more regions near the outer edge of the semiconductor wafer.

[0085] In a further embodiment, generating a pressure differential includes: allowing gas to flow through one or more pin holes that extend through a wall adjacent to and at least partially surrounding the outer edge of a semiconductor wafer, the wall having an inner surface facing the outer edge of the semiconductor wafer and an outer surface opposite the inner surface, and each pin hole defining an internal opening at the inner surface of the wall and an external opening at the outer surface of the wall.

[0086] In another embodiment, the internal opening defined by each pin hole has a first geometric area, and the external opening defined by each pin hole has a second geometric area, the second geometric area being larger than the first geometric area.

[0087] In some embodiments, each pin hole has a truncated shape, either a cone or a pyramid.

[0088] In yet another embodiment, causing the gas to flow includes causing the gas to flow along the outer surface of the wall.

[0089] In some other embodiments, the pressure differential includes a relatively lower pressure region at the external opening of the pin hole compared to the internal opening of the pin hole.

[0090] In some embodiments, the pressure difference draws the coating material to the outer edge of the semiconductor wafer.

[0091] In a further embodiment, the coating material has a viscosity greater than or equal to 100 cP.

[0092] In some embodiments, the coating material is either photoresist or polyimide.

[0093] In some other embodiments, a spin coater is provided for forming a layer on a semiconductor wafer having a central region and an outer edge. The spin coater includes: a rotatable chuck configured to hold the semiconductor wafer; and a nozzle configured to selectively deposit a coating material in the central region of the semiconductor wafer held on the rotatable chuck, the coating material forming the layer. The semiconductor wafer rotates about an axis by the rotation of the rotatable chuck, generating centrifugal force that causes the coating material to spread from the central region toward the outer edge of the semiconductor wafer. The spin coater also includes a flow field stabilizer having: an annular wall arranged such that when the semiconductor wafer is held to the rotatable chuck, the annular wall is close to and surrounds the outer edge of the semiconductor wafer, the annular wall having an inner surface facing the outer edge of the semiconductor wafer and an outer surface opposite the inner surface; and one or more pin holes extending from the inner surface through the annular wall to the outer surface, each pin hole defining an internal opening at the inner surface of the annular wall and an external opening at the outer surface of the annular wall. The spin coater also includes an airflow generator that generates airflow, at least a portion of which is directed to flow along the outer side of the outer surface of the wall of the flow field stabilizer and through the external opening of the pin hole.

[0094] In a further embodiment, the internal opening defined by each pin hole has a first geometric area, and the external opening defined by each pin hole has a second geometric area, the second geometric area being larger than the first geometric area.

[0095] In another embodiment, each pin hole has a truncated shape, either a cone or a pyramid.

[0096] In a further embodiment, the portion of the airflow flowing along the outer surface of the wall of the flow field stabilizer and passing through the external opening of the pin hole generates a local pressure difference, which includes a relatively low pressure region at the external opening of the pin hole compared to the internal opening of the pin hole.

[0097] In some additional embodiments, local pressure differentials are used to draw the coating material to the outer edge of the semiconductor wafer.

[0098] In some embodiments, the spin coater further includes a top cup portion having an annular lip extending inward toward an axis, the annular lip and the outer surface of the flow field stabilizer wall defining an annular gap between them, through which said portion of the airflow is guided.

[0099] In some embodiments, the annular gap has a width greater than or equal to 5 mm measured in the radial direction relative to the axis.

[0100] In some other embodiments, the portion of the airflow guided through the annular gap is in the range of greater than 50% and less than or equal to 90% of the airflow.

[0101] In a further embodiment, a spin-coating apparatus for forming a layer on a semiconductor wafer is provided. The spin-coating apparatus includes: a deposition machine for selectively depositing a coating material onto the semiconductor wafer; a suction cup for holding the semiconductor wafer and rotating it together with the suction cup to extend the coating material toward the outer edge of the semiconductor wafer; a wall adjacent to and at least partially surrounding the outer edge of the semiconductor wafer; and one or more pin holes extending through the wall, each pin hole defining an internal opening at an inner surface of the wall and an external opening at an outer surface of the wall. Suitably, a local pressure differential is generated at the pin holes by causing gas to flow along the outer surface of the wall and through the external opening of the pin holes, the local pressure differential being used to draw the coating material toward the outer edge of the semiconductor wafer.

[0102] In a further embodiment, the spin coating apparatus further includes: a controller for regulating the operation of at least one of the depositor and the suction cup; and a user interface that can be selectively used by a user to input instructions to the controller so that the controller regulates the operation of at least one of the depositor and the suction cup according to the instructions.

[0103] In yet another embodiment, the spin coating apparatus further includes an airflow generator for generating airflow along the outer surface of the wall and flowing through the external opening of the pin hole.

[0104] The foregoing has outlined features of several embodiments to enable those skilled in the art to better understand various aspects of this disclosure. Those skilled in the art will understand that they can readily use this disclosure as a basis for designing or modifying other processes and structures to achieve the same purposes and / or realize the same advantages as the embodiments described herein. Those skilled in the art should also recognize that these equivalent constructions do not depart from the spirit and scope of this disclosure, and that they can make various changes, substitutions, and modifications thereto without departing from the spirit and scope of this disclosure.

Claims

1. A method for forming a layer on a semiconductor wafer having a central region and outer edges, comprising: A coating material is deposited on the central region of the semiconductor wafer, the layer being formed by the coating material; The semiconductor wafer is rotated around an axis, and centrifugal force causes the coating material to spread from the central region to the outer edge of the semiconductor wafer; as well as A pressure difference is generated in one or more regions near the outer edge of the semiconductor wafer, wherein generating the pressure difference includes: The gas is guided to flow through a gap and along the outer surface of the wall of the flow field stabilizer through one or more pin holes to generate the pressure difference between the inner opening of the pin hole at the inner surface of the wall of the flow field stabilizer and the outer opening of the pin hole at the outer surface of the wall of the flow field stabilizer, wherein the semiconductor wafer is placed in the space formed by the top cup and the bottom cup, and the gap is between the upper flange of the top cup and the outer surface of the wall of the flow field stabilizer.

2. The method according to claim 1, wherein the upper flange of the top cup portion extends inward toward the axis.

3. The method according to claim 1, wherein: The inner opening defined by each of the pin holes has a first geometric area, and the outer opening defined by each of the pin holes has a second geometric area, the second geometric area being larger than the first geometric area.

4. The method of claim 3, wherein each of the pin holes has a truncated shape of either a cone or a pyramid.

5. The method according to claim 1, wherein the gas flows out of the top cup portion and into the bottom cup portion through an inlet formed in the annular lip of the bottom cup portion, and then flows between the sidewall of the intermediate cup portion and the sidewall of the bottom cup portion, which are housed in the cavity defined by the bottom cup portion.

6. The method of claim 1, wherein the pressure difference includes a relatively low pressure region at the external opening of the pin hole compared to the internal opening of the pin hole.

7. The method of claim 1, wherein the pressure difference draws the coating material to the outer edge of the semiconductor wafer.

8. The method according to claim 1, wherein the coating material has a viscosity greater than or equal to 100 centipoise.

9. The method according to claim 1, wherein the coating material is one of photoresist or polyimide material.

10. A spin coater for forming a layer on a semiconductor wafer having a central region and outer edges, comprising: Top and bottom portions; A rotatable suction cup is disposed within the space formed by the top cup and the bottom cup to hold the semiconductor wafer; and A nozzle is configured to selectively deposit a coating material in the central region of the semiconductor wafer held on the rotatable chuck, the coating material forming the layer, wherein the semiconductor wafer is rotated about an axis by the rotation of the rotatable chuck and centrifugal force is generated, causing the coating material to spread from the central region toward the outer edge of the semiconductor wafer; Flow field stabilizers, including: An annular wall, configured such that when the semiconductor wafer is secured to the rotatable chuck, the annular wall approaches and surrounds the outer edge of the semiconductor wafer, the annular wall having an inner surface facing the outer edge of the semiconductor wafer and an outer surface opposite the inner surface; and One or more pin holes extending from the inner surface through the annular wall to the outer surface, each pin hole defining an internal opening at the inner surface of the annular wall and an external opening at the outer surface of the annular wall, wherein a gap exists between the upper lip of the top cup portion and the outer surface of the annular wall of the flow field stabilizer; and An airflow generator generates airflow, wherein the airflow is guided through the gap and along the outer surface of the annular wall of the flow field stabilizer through the pin hole to create a pressure difference between the inner opening and the outer opening of the pin hole.

11. The spin coater according to claim 10, wherein: The internal opening defined by each of the pin holes has a first geometric area, and the external opening defined by each of the pin holes has a second geometric area, the second geometric area being larger than the first geometric area.

12. The spin coater of claim 11, wherein each of the pin holes has a truncated shape of either a cone or a pyramid.

13. The spin coater of claim 10, wherein at least a portion of the airflow flowing along the outer side of the outer surface of the annular wall of the flow field stabilizer and passing through the outer opening of the pin hole generates a local pressure differential, the local pressure differential including a relatively low pressure region at the outer opening of the pin hole compared to the inner opening of the pin hole.

14. The spin coater of claim 13, wherein the local pressure difference is used to draw the coating material to the outer edge of the semiconductor wafer.

15. The spin coater according to claim 10, further comprising: The middle cup portion is housed within a cavity defined by the bottom cup portion, wherein the airflow exits the top cup portion and flows into the bottom cup portion through an inlet formed in the annular lip of the bottom cup portion, and then flows between the sidewalls of the middle cup portion and the sidewalls of the bottom cup portion.

16. The spin coater of claim 10, wherein the gap is annular and has a width greater than or equal to 5 mm measured in the radial direction relative to the axis.

17. The spin coater of claim 16, wherein at least a portion of the airflow guided through the gap is in the range of greater than 50% and less than or equal to 90% of the airflow.

18. A spin-coating apparatus for forming a layer on a semiconductor wafer, comprising: A deposition machine that selectively deposits coating material on the semiconductor wafer and includes a top cup and a bottom cup. A suction cup holds the semiconductor wafer so that the semiconductor wafer rotates together with the suction cup, thereby spreading the coating material to the outer edge of the semiconductor wafer; A wall that is close to and at least partially surrounds the outer edge of the semiconductor wafer; as well as One or more pin holes extending through the wall, each of the pin holes defining an internal opening at an inner surface of the wall and an external opening at an outer surface of the wall, wherein gas is guided through a gap and along the outer surface of the wall through the pin hole to create a local pressure difference between the internal opening and the external opening of the pin hole, the local pressure difference being used to draw the coating material to the outer edge of the semiconductor wafer, the gap being between the upper flange of the top cup portion and the outer surface of the wall.

19. The spin coating apparatus according to claim 18, further comprising: The controller regulates the operation of at least one of the deposition machine and the suction cup; as well as The user interface can be selectively used by the user to input instructions to the controller, so that the controller adjusts the operation of at least one of the deposition machine and the suction cup according to the instructions.

20. The spin coating apparatus of claim 18, wherein the deposition machine further comprises: The intermediate cup portion is housed within a cavity defined by the bottom cup portion, wherein the gas flows out of the top cup portion and into the bottom cup portion through an inlet formed in the annular lip of the bottom cup portion, and then flows between the sidewalls of the intermediate cup portion and the sidewalls of the bottom cup portion.

Images