SYSTEM ARCHITECTURE OF MANUFACTURING OF SEMICONDUCTOR WAFERS

A post lithography resist treatment apparatus for treating a substrate having a resist layer thereon with a fluid layer thereover includes at least one post exposure bake chamber comprising a substrate support having a substrate support surface thereon, and an electrode, the electrode comprising an electrode body having a substrate support facing side, the substrate support facing side having at least one recess extending inwardly thereof, and at least one projection adjacent to the recess having a substrate support facing surface thereon, wherein the substrate support is moveable to position a substrate, when supported thereon, such that an fluid layer disposed on the substrate contacts the substrate support facing surface of the projection but does not fill the recess with fluid, and the substrate facing surface of the electrode body is spaced from the substrate.

BACKGROUND

Field

The present disclosure generally relates to methods and apparatus for processing a substrate, and more specifically to methods and apparatus for improving photolithography processes, more specifically methods and apparatus for a field guided post exposure bake of a resist layer, for example a chemically activated resist layer.

Description of the Related Art

Integrated circuits have evolved into complex devices that can include millions of components (e.g., transistors, capacitors and resistors) on a single chip. Photolithography is a process that is used in the fabrication of components on a chip. Generally the process of photolithography involves a few basic stages. Initially, a photoresist layer is formed on a substrate or over a film layer previously provided on the substrate, typically by spin coating wherein droplets of the photoresist in liquid form are dropped onto the surface of a spinning substrate to form a relatively uniform thickness thin layer of photoresist on the surface of the substrate or film layer thereon. One type of a photoresist, a chemically amplified photoresist, commonly includes a resist resin and a photo acid generator. The photo acid generator, upon exposure to electromagnetic radiation in the subsequent exposure of the photoresist, selectively alters the solubility of the photoresist which is useful in the development of the resist process. The electromagnetic radiation may have any suitable wavelength, for example, a 193 nm ArF laser, an electron beam, an ion beam, or other suitable source. Excess solvent may then be removed in a pre-exposure bake process.

In a resist exposure stage of the photolithography process, a photomask or reticle is used to selectively expose certain regions of the substrate to the electromagnetic radiation. Other exposure methods may be mask less exposure methods where a pattern is written into the photoresist, for example by scanning a laser beam thereon. Exposure to appropriate electromagnetic radiation decomposes the photo acid generator, which as a result generates acid and results in a latent acid image in the resist resin. After exposure, the substrate is typically heated in a post-exposure bake process. During the post-exposure bake process, the acid generated by the photo acid generator reacts with the resist resin, changing the solubility of the resist which is useful during the subsequent development process of the resist.

After the post-exposure bake, the substrate, and, particularly, the photoresist layer, is developed to remove the soluble portion thereof and leave a patterned resist layer, or “mask” on the substrate, after which the substrate is rinsed to remove the developer and any remaining byproducts of the developing reaction. Depending on the type of photoresist used, regions of the substrate that were exposed to the electromagnetic radiation may either be resistant to removal or more prone to removal. The mask pattern is transferred to an underlying portion of the substrate or film layer using a wet or dry etch process such as reactive ion etching.

One desire in the evolution of chip designs is to provide chips having faster switching circuitry and a greater circuit density. The demands for greater circuit density necessitate a reduction in the dimensions of the integrated circuit components. As the dimensions of the integrated circuit components are reduced, more elements are required to be placed in a given area on a semiconductor integrated circuit. Accordingly, the lithography process must be capable of forming mask layers which can be used to form even smaller features onto a substrate, and lithography must do this so precisely, accurately, and without damage to the underlying substrate or layers previously formed and processed thereon. In order to precisely and accurately transfer features onto a substrate, high resolution lithography may use a light source that provides radiation at short wavelengths. Short wavelengths help to reduce the minimum printable size on a substrate or wafer. However, short wavelength lithography suffers from problems, such as low throughput, increased line edge roughness, and/or decreased resist sensitivity.

In a recent development, an electrode assembly is utilized to generate an electric field on or through a photoresist layer disposed on the substrate prior to or after an exposure process so as to modify the chemical properties of the portion of the photoresist layer into which the electromagnetic radiation is transmitted, to improve the resolution of the developed resist features resulting from lithography exposure and development. In the process, an electrode is contacted with a fluid provided on the resist layer on a substrate held on a grounded pedestal, to allow current to pass through the resist layer or an electric potential applied to the resist layer. However, the challenges in implementing such systems have not been fully resolved. For example, the fluid is dispensed onto the substrate, after which the substrate, the electrode, or both are moved to position the fluid layer into contact with the substrate. It is known that during this positioning of the fluid layer to contact the electrode, gas present in the process chamber can become trapped as gas pockets between the electrode and the fluid, resulting in a discontinuous electric circuit between the resist layer on the substrate and the electrode across the face of the resist or electrode. This results in non-uniform processing of the resist layer over its surface. It is also known that the field guided post exposure bake process evolves gases which can also cause gas pockets which interfere with the passage of the electric current or imposition of the electric potential through the fluid present between the photoresist layer and the electrode, and result in non-uniform processing of the resist. Additionally, reaction byproducts of the process contacting the electrode surface in contact with the fluid can react therewith, locally changing the electrical characteristics of the electrode where the reaction product contacts the electrode.

Therefore, there is a need for improved methods and apparatus for improving photolithography processes.

SUMMARY

In one aspect hereof, a post lithography resist treatment apparatus for treating a substrate having a resist layer thereon with a fluid layer thereover includes at least one post exposure bake chamber comprising a substrate support having a substrate support surface thereon, and an electrode, the electrode comprising an electrode body having a substrate support facing side, the substrate support facing side having at least one recess extending inwardly thereof, and at least one projection adjacent to the recess having a substrate support facing surface thereon, wherein the substrate support is moveable to position a substrate, when supported thereon, such that a fluid layer disposed on the substrate contacts the substrate support facing surface of the projection but does not fill the recess with fluid, and the substrate facing surface of the electrode body is spaced from the substrate.

In another aspect, a method of performing post lithography resist treatment of a resist layer coated on a substrate, includes providing at least one post exposure bake chamber, the post exposure bake chamber including a substrate support and a fluid dispenser, positioning the substrate onto a substrate support having a substrate support surface thereon, and rotating the substrate support and dispensing a fluid onto the exposed resist coated surface of the substrate thereon during the rotation of the substrate support, providing an electrode, the electrode comprising an electrode body having a substrate support facing side, the substrate support facing side having at least one recess extending inwardly thereof and at least one projection, adjacent the recess, having a substrate support facing surface thereon, raising the substrate support to position the fluid layer disposed on the substrate in contact with the substrate support facing surface of the projection without filling the recess with fluid and maintaining a gap between the substrate facing surface of the electrode and the substrate, and powering the electrode.

In a further aspect hereof, a post lithography resist treatment apparatus includes at least two post exposure bake chambers stacked one over the other, each post exposure bake chamber including a substrate support having a substrate support surface thereon, and an electrode, the electrode having an electrode body comprising a substrate support facing side, the substrate support facing side having at least one recess extending inwardly thereof and at least one projection, adjacent the recess, having a substrate support facing surface thereon, wherein the substrate support is moveable to position a substrate, when supported thereon, such that a fluid layer disposed on the substrate contacts the substrate support facing surface of the projection but does not fill the recess with fluid, and the substrate facing surface of the electrode is spaced from the substrate.

DETAILED DESCRIPTION

The present disclosure generally relates to methods and apparatus for post exposure bake processes, in particular a field guided post exposure bake process. Methods and apparatus disclosed herein assist in reducing line edge/width roughness and improve exposure resolution in a photolithography process for semiconductor applications.

The methods and apparatus disclosed herein improve the photoresist sensitivity and productivity of photolithography processes. The random diffusion of charged species generated by the photo acid generator in the chemically amplified resist during a post exposure bake procedure contributes to line edge and line width roughness and reduced resist sensitivity, which is ameliorated by the exposure thereof to a voltage potential or electric current during the post exposure bake process.

Among the several considerations regarding using an electrode to pass a current through a fluid present between the electrode and the photoresist layer or apply a potential thereto are the entrainment of gas bubbles in the fluid as it is dispensed onto the substrate, the trapping of chamber gas between the electrode and the fluid as the substrate is lifted to contact the fluid with the electrode, and the evolution of gas from the resist being electrically treated during the baking thereof, which can result in gas pockets of bubbles in the fluid being present across a portion of the electric circuit between the electrode and the resist layer through the fluid. These evolved gases can also react with the surface of the electrode, resulting in localized detrimental changes to the electrical properties of the electrode surface contacting the fluid. The presence of the gas pockets causes non-uniformities within the electric field applied to the resist layer and therefore increases the defectivity of the photoresist after the post-exposure bake process. For example, where gas is trapped between the fluid and electrode as they are brought into contact with one another, portions of the electrode where the trapped gas is present will not be in the electrical circuit with the resist, and non-uniform resist processing will occur. Likewise, where bubbles of evolved gas are buoyant in the fluid, they rise therein to contact the substrate facing side of the electrode, through which the electric field is applied to the substrate or the electric current is passing between the fluid and electrode. Although the substrate is rotating under the electrode, these bubbles or gas pockets formed as the fluid and electrode were brought into contact can become trapped between the substrate and the electrode, either at a specific locales on the electrode, or at a circumferential location thereon as they are induced to travel in the rotation direction of the substrate. The gas pockets are electrically insulating, and thus the presence of gas pockets causes differences in the total current or total potential voltage times the time of exposure thereto applied to different regions of the substrate and the photoresist layer thereon, resulting in differences in the clarity of the edges of the later developed lines and features of the photoresist. Likewise, detrimental evolved gaseous products of the baking of the photoresist can reach the electrode surface, locally detrimentally changing the electrical characteristics thereof. The present apparatus and methods described herein beneficially reduces the likelihood of gas pockets, including those with evolved gasses detrimental to the electrical characteristics of the electrode surface, being maintained between the photoresist layer and the electrode assembly, and thus differences in the resulting developed photoresist image across the face of the substrate.

Here, a patterned electrode assembly, such as those described herein, is utilized to apply an electric field to the photoresist layer during the post expose bake of the substrate and resist layer thereon. By using a patterned electrode assembly, wherein the electrode has extended regions which are in contact with the fluid medium, and recessed regions therebetween, gas evolved during the treatment process both as byproducts and as released air will pass through the fluid by natural buoyancy thereof in the direction of the electrode and into a recess region thereof and thereby not block the electric current flow between the substrate and the portion of the electrode in contact with the fluid where this gas as a gaseous byproduct or a gas pocket would otherwise remain. Where the gas is initially contacting an extended region of the electrode, the relative rotation of the electrode and substrate will result in these gases being swept to a recess region where their natural buoyancy can trap them.

In the aspects of a post exposure bake system herein, a process chamber generally includes a fixed electrode located over a rotatable, vertically moveable, substrate support. The electrode includes recesses extending inwardly thereof, such that projecting portions of the electrode where the recesses are not present can contact the electricity carrying fluid on the substrate, but any gas on the fluid, between the fluid and the projecting portions, or evolved during processing can reach a recessed portion. In some aspects, the electrode also includes relief passages, here in the form of slots or openings, which extend from the recesses to the non-substrate facing side of the electrode, such that an increase in the gas pressure in a recess, caused by increases in the amount of gas flowing into a recess, cannot occur as the gas is ventable therefrom.

FIGS. 1A, 1B and 1Care schematic cross-sectional views of an immersion field guided post exposure bake chamber100according to one embodiment described herein. The immersion field guided post exposure bake chamber100includes a substrate processing apparatus101and a module body102which provides a sealable enclosure for the substrate processing apparatus101. An opening, or port193in the sidewall of the module body is provided for placement of a substrate into, or removal of a substrate from, the module body102. A door193a, shown open inFIG. 1A, is moveable located over the port193in the wall of the module body102to selectively seal the port193to isolate the volume within the module body102from the environment surrounding the module body102during substrate processing, and to open to allow substrates to be placed into, and retrieved from, the module volume of the module body102. Here, the post exposure bake chamber100is generally configured to include a dispense arm190for dispensing a fluid onto the upper, resist coated, surface of a substrate150, a pedestal106including a substrate support176configured to support and rotate the substrate150during the application of the fluid thereonto, during the application of an electric field thereto, and thereafter to remove the fluid. An electrode115is positioned over the substrate support176and configured to supply power as a desired voltage potential (voltage mode) or a desired current (current mode) through the fluid to the substrate150, and, a catch ring185is positionable about the circumference of the substrate support176after processing of the substrate150, such that rotation of the substrate support176can be performed at a sufficient rotational speed to cause the fluid on the substrate150to be accelerated off of the substrate150and into a trough236in the catch ring185. A gas port127is provided through the wall of the module body102to provide gas into the module volume90. Air, or a relatively inert gas such as Nitrogen or inert Argon can be introduced to the inner volume of the module body through the gas port127. A pump port127likewise extends through the wall of the module body102, and is connected to a suction source operable at a pressure lower than that in the module volume90, for example a house exhaust of the fab where the chamber100is installed or a vacuum pump125such as a roughing pump. InFIG. 1A, the upper ends or heads of the support pins252are positioned above the substrate support176and a substrate150is shown positioned on the heads of these support pins252. In this position, the substrate150can be placed into, or removed from, the module body102via the port193in the sidewall thereof using the end effector of a robot blade250. InFIG. 1Bthe substrate150is positioned by the substrate support176to receive the fluid thereon prior to the processing thereof with the electric field, and the circumferential catch ring185surrounds the substrate support176to receive the fluid therein, as well as positioned when the fluid is accelerated off of the substrate150after the processing thereof.FIG. 1Cshows the substrate support176fully lifted toward the electrode assembly115, such that the fluid117on the substrate150contacts the electrode170of the electrode assembly115across the electrode facing surface of the substrate150.

The substrate processing apparatus101includes the base assembly110and then electrode assembly115. The module body102serves as a chamber body which surrounds the substrate processing apparatus101and forms the enclosed module volume90therein. The base assembly110and the electrode assembly115are disposed within the module volume90. The base assembly110includes the substrate support176configured to receive and support a substrate thereon, such as the substrate150shown. The substrate support176is configured to hold the substrate150thereon, rotate the substrate generally about the center of the electrode facing side thereof, and to heat the substrate to a post exposure bake temperature, for example about 100° C. to about 150° C. or about 150° C. to about 500° C. The electrode assembly115is disposed opposite to and faces the base assembly110, i.e., it faces the base assembly110and thus the substrate support176at the location thereof where the substrate150is located and is configured to apply an electric field to the substrate150and thereby perform a field guided post exposure bake process the substrate150disposed thereon as will be further described herein. The volume between the electrode assembly115and the substrate150when the substrate150is lifted to the position thereof inFIG. 1Cforms a process volume114and the process volume114is filled with a process liquid, here a fluid capable of electric current passage therethrough during substrate processing. This fluid can be for example a fluid in liquid phase with a boiling point above 150° C., a resistivity range 107-1012Ωcm, low reactivity with photo resist, for example a highly resistive fluid based on a fluorocarbon like Galden® or fluoroinert. The center C2of the electrode115assembly, and thus of the substrate facing side thereof, is in some aspects hereof offset radially from the center of rotation C1of the substrate support176. The pedestal106includes a rod shaped pedestal support shaft128, the centerline of which passes through the center of rotation C1of the substrate support176, and upon which the substrate support176is supported.

The base assembly110includes the substrate support176supported on the rod shaped pedestal support shaft128, and having a substrate support surface174on the electrode assembly115facing side thereof and on which the substrate150is supported. As shown inFIGS. 1C and 3, the substrate support176is a generally disk shaped member having an outer peripheral circumferential surface200(FIG. 2). An edge ring202which functions as a circumferential fluid dam is coupled to the outer peripheral circumferential surface200of the pedestal106. The inner surface of the edge ring202forms the circumferential outer boundary of the process volume114. The substrate support surface174is the upper surface of the substrate support176, in other words, the surface of the substrate support176which faces the electrode assembly115. Here, the substrate support176is configured as a vacuum chuck, wherein a vacuum line204is coupled, through a rotary union207to a vacuum passage206in the pedestal support shaft128which opens at the substrate support surface174. The substrate support surface174includes a plurality of circular grooves208generally centered on the opening210of the vacuum passage206at the substrate support surface174, and a plurality of radial grooves, here two radial grooves201, extending radially from the opening210of the vacuum passage206opening210at the substrate support surface side thereof and inwardly of the substrate support surface174. When a substrate is located on the substrate support surface, a slight vacuum on the order of 100 to 250 torr less than the pressure within the module volume90is pulled through the vacuum line204and vacuum passage206. The vacuum results in the substrate150being pulled against the surfaces of the non-grooved portions of the substrate support surface174, or pushed thereagainst by the higher pressure in the module volume90. A plurality of substrate support pins252, having enlarge upper heads, extend through pin openings253(FIG. 3) extending through the pedestal. The lift pins252terminate below the support pedestal106with enlarged landing pads255. With the support pedestal106in its lowest position within the module body, as shown inFIG. 1A, the heads of the pins252extend above the substrate support surface174, because the landing pads255engage the base of the module body102. In this position, a substrate150can be placed on, or removed from, the heads of the pins252. As the substrate support pedestal106is moved in the direction of the electrode115, the heads of the pins252become recessed into the substrate support surface174in an enlarged upper portion of the pin openings253, and the enlarged landing pads255are lifted off of the base of the module body102. The landing pads255may alternatively be fixed to the base of the module body102, in locations where the lower ends of the lift pins252will contact them as the substrate support174is lowered.

The substrate support pedestal106and edge ring202are configured so that the outer circumferential surface of the substrate150can be engaged against the inner surface of the edge ring202to form a circumferential seal between the edge of the substrate150and the edge ring202, to prevent fluid from contacting the support surface174when present on the substrate150surface facing the electrode115as shown inFIG. 2. The substrate support pedestal106includes a support body126forming at the upper surface thereof the substrate support surface174and the shaft128extending from the side thereof opposite of the substrate support surface174. The vacuum passage206extends therethrough to supply the vacuum between a substrate150and the substrate support surface174. The edge ring202, disposed circumferentially around the substrate support pedestal106, includes an inner outwardly extending frustoconical surface212, a lower attachment portion214, an upper annular surface216, and an outer frustoconical surface218. The inner outwardly extending frustoconical surface212of the edge ring202extends beyond and above the substrate support surface174a distance greater than the thickness of a fluid layer220which is formed over the substrate150during processing thereof, where the fluid is used as the conductive path between the electrode115and the substrate150, including a resist layer222on the substrate150. The outer circumference of the pedestal106, is configured such that the bevel224on the side of the substrate facing the substrate support surface174of the pedestal106extends outwardly thereof and the bevel224, or the intersection of the bevel224and the outer circumferential face226of the substrate150engage against the inner outwardly extending frustoconical surface212of the edge ring202. Alternatively, a seal ring grove can be extended inwardly of the substrate support surface174side of the support pedestal106at a location adjacent to the outer circumference thereof, and a seal ring provided therein to seal against the substrate support facing side of the substrate150.

The substrate support176includes at the lower outer circumference thereof an annular recess221having an upper annular recess wall223, from which the outer peripheral circumferential surface200of the substrate support pedestal106extends upwardly and outwardly to meet the substrate receiving surface174of the support pedestal106. A plurality of through openings227a(only one shown) extend through the lower attachment portion214of the edge ring202and into mating threaded openings227extending inwardly of the upper annular recess wall223of the support pedestal, and a plurality of threaded fasteners229extend thereinto to secure the edge ring202to the support pedestal106. The outwardly extending frustoconical surface212of the edge ring202is thus brought into facing contact with the outer peripheral (frustoconical) circumferential surface200of the substrate support pedestal106.

The catch ring185is configured to receive the fluid and isolate the fluid from the module volume90after the substrate150has been treated using the electrode assembly115. After the substrate150is processed by the application of the electric field via the electrode170of the electrode assembly115, the substrate support pedestal106is lowered, and the catch ring185is lifted, to the positions thereof inFIGS. 1B and 2, to position the catch ring185circumferentially around the substrate support176while the support pins252are still suspended in the substrate support pedestal and thus spaced above the base of the module body102. The catch ring185is a generally annular member, having a circumferential inner wall230and a circumferential outer wall232, wherein the lower portion of the outer wall232is disposed at a 90° angle directed upwards from an annular base234of the catch ring185, the inner surface233thereof extending a height or distance therefrom sufficient to, in conjunction with the inner surface239of the inner wall230, form a trough236to catch and capture liquid accelerated off of the substrate150by rotation thereof on the substrate support pedestal106. This liquid will flow down the sides of the inner surface233of the outer wall into the trough236of the catch ring185.

During the rotation of the substrate pedestal106to accelerate the fluid off of the surface of the substrate150, the liquid is accelerated to flow across the inner outwardly extending frustoconical surface212of the edge ring202, which guides the flow of the liquid against the inner sidewall233of the outer wall232of the catch ring185which is cooperatively arranged for this purpose. Thus, the catch ring outer wall232includes a lower outer wall235extending from the annular base wall234a greater distance than does the catch ring inner wall230thereof from the annular base234of the catch ring185, and an upper wall237, the portion of the outer wall inner surface233athereof angled radially inwardly toward the center of the catch ring185. The angle α formed between the lower side of the plane of the inner outwardly extending frustoconical surface212of the edge ring202with the inner surface233portion of the upper wall237is greater than 90°, which helps ensure that the liquid accelerated off of the substrate150and guided toward the catch ring185along the directional vector of the plane of the inner outwardly extending frustoconical surface212of the edge ring202will tend to flow downwardly along the inner surface233and into the trough236. Although the upper wall237intersects the outer wall232at an angle, the inner surfaces233a,233thereof may blend together as a continuous curve. A catch ring drain opening186connects the trough236of the catch ring185to a fluid reservoir121(FIGS. 1A to 1C) through a catch ring drain line238. Liquid collecting in the trough236flows through the catch ring drain186into the reservoir121through the catch ring drain line238.

The catch ring185is supported by a support shaft240extending through sealed opening through the base of the module body102. A bellows or other structure, not shown, is used to seal the opening. The portion of the support shaft240disposed therethrough is coupled to a ring driver support plate241, which is threadingly coupled to a first threaded shaft243. The first threaded shaft243is rotatable about the longitudinal axis direction thereof and is turned or rotated about its longitudinal axis in two directions by a catch ring motor242. Rotation of the first threaded shaft243in the first direction causes the ring driver support plate241to move away from the base of the module body102and lower the ring support shaft240, and thus the catch ring154, within the module volume90. Rotation of the first threaded shaft243in the opposite, or second direction causes the ring driver support plate241to move toward the base of the module body102and raise the ring support shaft240, and thus the catch ring154, within the module volume90. Here, the catch ring185is locatable in a recessed or lowered position as shown inFIG. 1Cwhere it is entirely below the port193, and in a fluid capture position as shown inFIG. 1B. In the fluid capture position, the upper surface216of the edge ring202is at least at the same elevation, or greater, from the base of the module body102as the port193, and the support pedestal106is lifted to a position sufficient to lift the enlarged landing pads255of the support pins252or the support pins252themselves when the landing pads255are affixed to the base of the module body102, off of the base of the module body as shown inFIG. 1B. Thus, when the substrate support176rotates at an angular velocity to accelerate the fluid to a sufficient velocity to reach the catch ring185and flow along the inner surface233of the outer wall232into the trough236, the landing pads255are located in free space above the base of the module body102allowing the substrate support176to rotate without interference of the support pins252with the base of the module body102.

The substrate support pedestal106, and thus the substrate support surface174, is moved toward and away from the electrode115by the movement of the pedestal support shaft128through a sealed opening through the base of the module body102. Again here, the opening is sealed using a bellows, not shown, or other sealing arrangement. The support shaft128is supported, exteriorly of and below the module body102, on a pedestal support plate136. The pedestal shaft128is coupled to the bottom surface of the substrate support176portion of the substrate support pedestal106. The shaft128extends from the module volume90through an opening within the module body102. The shaft128enables the pedestal106structure, and thus the substrate support176thereof, to be moved between a substrate loading position (FIG. 1A), a process position thereover (FIG. 1C), and a fluid removal position (FIG. 1B) intermediate of the substrate loading and the substrate processing positions. The portion of the pedestal shaft128extending outwardly of the module body102is supported on the pedestal support plate136. The pedestal support plate136includes a threaded opening therethrough, through which a second threaded shaft205is threadingly extended therethrough. The second threaded shaft205is coupled to a pedestal lift motor209. The pedestal lift motor209moves or rotates the second threaded shaft205about its longitudinal axis in a first and an opposite second direction. As the second threaded shaft205rotates in the second direction, the pedestal support plate136and thus the attached pedestal shaft128and the substrate support1761is raised. As the second threaded shaft205is rotated in the opposite, first direction, the pedestal shaft128, and the thus the substrate support176, retract away from the electrode115assembly. The portion of the shaft128extending underneath the module body102is also connected to a pedestal rotation motor211supported on the pedestal support plate136. The pedestal rotation motor211supported on the substrate support plate136is coupled to the base of the pedestal shaft128by a drive shaft thereof (not shown). The pedestal rotation motor211rotates the pedestal shaft128and thus the substrate support pedestal106at a rotation speed such as 60 rpm during the processing of the substrate150with the electrode115and electric field, or at 120 rpm during the removal of the fluid from the substrate150.

The substrate support176is electrically connected to ground172via the pedestal shaft128and thus electrically grounded. Grounding the substrate support176enables better control of the electric field between the electrode assembly115and the substrate150. The connection to ground172is, for example, via slip rings on a rotary union207on the pedestal shaft128as shown inFIG. 1B. The substrate support178is configured of an electrically conductive material, with an electrical resistivity of less than about 1×10−3Ω·m, such as less than 1×10−4Ω·m, such as less than 1×10−5Ω·m. The contact resistance between the substrate support176portion of the pedestal106, and the substrate150, has a greater impact on the ability of the pedestal106to electrically ground the substrate150than the resistivity of the pedestal106itself. In embodiments described herein, the contact resistance between the substrate support176and the substrate150is less than about 1×10−3Ω, such as less than about 1×10−3Ω. In some embodiments, the substrate support176is a conductive ceramic or metal such as an aluminum, a silicon carbide, a doped silicon carbide, or a dopes silicon material.

One or more heating elements148are disposed in the substrate support176below the substrate support surface174. The one or more heating elements148are, for example, cable heaters forming two or more annular heating zones about the center of the support surface174to heat the substrate on the substrate support surface174to a uniform post exposure bake temperature. The heating elements148are disposed adjacent to, and immediately below, the substrate support surface174to reduce the thermal mass between the resistive heating elements and the substrate150. This increases the speed at which the resistive heating elements heat the substrate150during processing. The resistive heaters are electrically powered, and the power is supplied via wiring extending through the pedestal support128and connected, by slip rings (not shown), to a variable power supply (not show).

A chemical dispense arm190is fluidly connected to the reservoir121through a feed line138and a pump140to dispense liquid from within the reservoir121onto a substrate150supported on the pedestal106. The dispense arm190is a generally “L” shaped tube, having a first portion141extending inwardly of the base of the module body102through a sealed opening sealed by a bellows (not shown) or other seal, and a second portion143extending therefrom within the module body102and generally parallel to the substrate support surface174of the pedestal106and terminating at a nozzle191. A dispense arm motor145is coupled to the end of the first portion extending outwardly of the module body102, and is controlled to rotate the first portion141of the dispense arm190to position the second portion143thereof relative to the substrate150on the substrate support pedestal106and relative to the adjacent sidewall of the module body102. The second portion143of the dispense arm190is moveable such that it is either arranged to extend generally parallel to the adjacent wall of the module body102, or extend over a substrate150on the substrate support surface174of the pedestal106, such that the nozzle191is disposed directly over the center of the substrate150. In the location thereof inFIG. 1B, fluid117is dispensed from the reservoir121and through the nozzle by pumping action of the pump140, while the substrate is rotated at a desired speed about its center C1, to spread the fluid117over the resist layer coated on the substrate150.

In one aspect, as shown inFIGS. 4 to 7hereof, the electrode assembly115includes an electrode170and a hood104disposed around and covering at least a portion of the electrode170, the hood104covering the upper side of the electrode170and supporting the electrode170off of the upper wall of the module body102. The electrode170is configured, for example, as a conductive mesh or a finely perforated electrode plate. The electrode170is permeable to allow gas to pass therethrough, for example through perforations, mesh, pores, or other gas permeable structures. The electrode170is utilized in order to reduce the number and size of gas bubbles or gas pockets which would otherwise become trapped under the electrode assembly115as the electrode assembly115is submerged into the process fluid, and resulting from gas evolved from the resist layer during the field guided post exposure bake thereof. The electrode170in some embodiments is configured of a non-metal electrically conductive material, such as a silicon carbide, such as a doped silicon carbide. In other embodiments, the electrode170is configured of a conductive metal, such as a copper, aluminum, platinum, or a steel. The electrode170is electrically coupled to a first power source118. The first power source118is configured to apply power to the electrode170. In some embodiments, an electrical potential of up to 5000 V is applied to the electrode170by the first power source118, such as less than 4000 V, such as less than 3000 V.

In one aspect as shown inFIGS. 4 to 7, the substrate facing face171of the electrode170contains a pattern of vent channels182as the recesses and protrusions183covering the entirety of the substrate facing face171of the electrode170. In this aspect of the electrode170, a plurality of circular channels182a-n, where n is a whole number integer, extend inwardly of the substrate facing face171of the electrode170, and these circular vent channels182are annularly spaced apart by circular protrusion181a-n, and are located from the center of the substrate facing face171of the electrode170such that the outer circumferential surface of the electrode170extends into the nth projection181n, generally extending as a right annular projection. Here, for clarity, only seven channels are shown, it being understood that a greater or lesser number thereof may be employed. At the center of the electrode170is a protrusion183ahaving a diameter D surrounded by a first annular vent channel182a. The next annular channel182bis formed the radial span of diameter D away from and outwardly of the first annular channel, thus forming a second right annular protrusion183bfollowing a circular path centered on the first protrusion181a. This pattern continues, with each additional protrusion181c-nhaving a width, in the radial direction from the central protrusion181a, of diameter D. Each vent channel182a-nchannel has a depth extending inwardly of the electrode170of for example 0.1 mm to on the order of 2.0 to 3.0 cm, such that the protrusions183extend to a height away from the substrate facing face171the same distance as the depth of the annular channels182. Inwardly of the non-substrate facing face177of the electrode170extend a plurality of longitudinal exhaust channels180, separated by longitudinally extending fins181as shown inFIGS. 6 and 7. These exhaust channels180extend in a generally straight line path and terminate at their opposed ends inwardly of the outer cylindrical surface of the electrode170. The exhaust channels extend across the vent channels180and intersect with them inwardly of the electrode170to form a vent passage for the gas evolved during processing of the substrate150. The material of the fins181contacts and supports the material of the protrusions181a-n. For example, the electrode170can be machined from a solid block of a material such that the fins181and protrusions183are of a contiguous portion of the material stock. The exhaust channels180here open at the non-substrate facing face177of the electrode170. Here, the hood104includes a circumferential flange165and a generally circular, in plan view, ceiling161spaced from the non-substrate facing face177of the electrode170, to form a plenum “P” over the adjacent vent channels180. This plenum P is coupled through an exhaust opening167in the ceiling161to an exhaust, for example the factory exhaust system leading to a scrubber, to allow the gas evolved during field guided post exposure bake of the resist layer to escape from the module body102. Absent this exhaust paradigm, where a large volume of gas is evolved from the resist layer, it could be possible to fill one of the vent channels180and thereby allow gas to aggregate on the electrode surface facing the substrate150and disrupt the uniformity of processing of the resist layer. The vent channels180here are positioned in parallel to one another so that the longest vent channel180extends generally across the center of the electrode170, with each of the vent channels180nsequentially positioned on either side of this longest channel180abeing smaller in length than the one adjacent thereto on the longest channel180bside thereof. The end of each vent channel180is spaced from the outer circumferential surface of the electrode, and is curved in to follow the contour of the outer circumferential surface of the electrode170.

FIGS. 8 to 10show certain details of another aspect of the electrode assembly115wherein a needle electrode170′ is provided and it includes as projections a plurality of needle like mesas300extending from a base surface302of the needle electrode170′. As best shown inFIG. 10, the mesas300here are each rectangular in section, having four outer walls304a-d, each of the adjacent outer walls disposed at an approximately 90° angle to one another. Opposed walls304a, chave a width of x, and the opposed walls304b,dhave a width of y, where x and y are on the order of 0.1 mm to two to three cm. Here, each mesa300includes a substrate facing mesa surface306having a surface area of x times y, as the surface thereof distal to the base surface302of the needle electrode170′. The substrate facing mesa surfaces306of the mesas300are coplanar with one another within machining tolerances. The substrate facing mesa surfaces306are disposed inwardly of the fluid117when the substrate is positioned as shown inFIG. 1Cand provide the electrical connection of the electrode170′ with the fluid117on the substrate150. Here, the mesas300extend as a contiguous extension of the electrode170′ from the base surface302, for example by the mesas300being machined into a planar electrode surface. The mesas may also be otherwise adhered to the base surface302, such as by being configured as pins that extend inwardly of the base surface302, or other connection paradigms. The mesas300are shown, inFIG. 8, to be arranged in a rectangular grid pattern and evenly spaced from one another along interstices of the rectangular grid, although other arrangements of mesas300extending from the base302of the needle electrode170′, such as a triangular or polygonal grid, and non-uniform spacings therebetween, are contemplated.

Here, the ratio of the collective sum of the surface areas of the substrate facing mesa surfaces306to the sum of the collective sum of the surface areas of the substrate facing mesa surfaces306and the area of the base surface302extending therebetween from which they extend is one the order of 0.2 to 0.8, i.e., 20 to 80% of the total area of the needle electrode170′ on the side thereof facing the substrate150is the substrate facing mesa surfaces306.

Here, the open space between the protrusions, i.e., between the mesas300is open across the circumference of the needle electrode170′, such that it is unlikely that sufficient gas evolved from the resist during the field guided post exposure bake process can fill this large open area to extend over a substrate facing mesa surface306. However, vent holes308can be provided through the base302of the electrode170′. Like the electrode170ofFIGS. 5 to 8, the needle electrode170′ is coupled to the hood104to provide an exhaust plenum such as plenum P as shown inFIGS. 5 and 6hereof over the back side of the needle electrode170′ into which these vent holes308communicate, and the plenum can likewise be exhausted to a house exhaust or other exhaust. The needle electrode170′ is connected to the hood104in the same manner as electrode104.

The hood104is electrically insulating. For example, the hood104is made from an electrically insulating material that reduces the flow of electric fields therethrough. The hood104being fabricated from an insulating material is beneficial in that hood104isolates the electrode170or needle electrode170′ from the walls of the module body102. The hood104is shaped to surround an upper surface and the side surfaces of the electrode170. The hood104also at least partially encloses a monitor electrode (not shown) overlying the electrode170(or needle electrode170′), and a spacer (not shown) may be disposed between the electrode170(or needle electrode170′) and the monitor electrode and between the hood and the monitor electrode, or the monitor electrode is otherwise electrically isolated from the hood104and the electrode170(or needle electrode170′). In some embodiments the hood104is an electrically conductive material with an electric resistivity of less than about 1×10−3Ω·m, such as less than 1×10−4Ω·m, such as less than 1×10−5Ω·m. In some embodiments, a metal, a metal alloy, or a silicon carbide material hood104is utilized. The hood104is suspended from the inner surface of the upper wall of the module body102, and where the hood104is conductive, an electrically insulative hood spacer (not shown) is connected to the hood, and the hood spacer177is connected to the upper inner surface of the module body102, to electrically isolate the hood104from the module body102.

FIG. 11is a flow chart illustrating one embodiment of a process for a post exposure bake. In a first action1010, a substrate150having a lithographically exposed resist layer thereon enters the chamber through the chamber port193and is positioned onto support pins252by a robot blade250. The robot blade250is configured to enter the module body102through the port193, lower the substrate150onto the heads of the support pins252, and then retract outwardly of the module body through the port193. The support pins252, catch ring185and support pedestal106are positioned as shown inFIG. 1Aduring this procedure. Once the substrate150is loaded onto the pins, the pedestal106is lifted by the pedestal motor209to meet the substrate150in a second action1020. A vacuum is applied through the pedestal106to releasably secure the substrate150to the substrate support surface174of the pedestal106, and the substrate150is heated by the heating elements148. The dispense arm190is then swung by the dispense arm motor145to the dispensing position above the substrate150. The pedestal106is rotated about its center by the pedestal rotation motor207and as the pedestal106rotates, process fluid in the form of a conductive fluid is dispensed onto the substrate by the dispense arm in a third action1030. The fluid stops being dispensed after the fluid has reach a sufficient level on the substrate for process, based on the volume of fluid dispensed. Once the desired volume of the fluid is dispensed, the dispense arm190support is rotated to move the dispense nozzle191ato the side of the chamber so that it is no longer over the pedestal106and will not interfere with vertical movement of the pedestal106or the catch ring185toward the electrode170. At action four1040the pedestal motor209rotates the second threaded shaft205to lift the pedestal106upwardly in the module volume90to cause the substrate facing surface of the electrode assembly, for example the substrate facing mesa surfaces306of electrode170′ or the annular faces163of electrode170to extend just inwardly of the fluid. During the process, Nitrogen is pumped at a low pressure into the module volume90through the gas port127in the module volume for the nitrogen line. Once the fluid is in proper contact with the electrode170, at a fifth action1050, the electrode applies a current the process liquid or is charged to a voltage potential, while the pedestal is rotated at up to about 60 rpm to perform the field guided post exposure bake process. If gas evolves during the post exposure bake process, this gas is swept off the surface of the electrode170submerged in the fluid by the shear of the fluid which is also rotating as a result of the rotation of the support pedestal106. Thus, the gas, which is buoyant in the fluid, collects into the recesses of the electrode, for example the recesses formed between the fins181or mesas300thereof, and move into the plenum between the body of the hood104and the electrode170or170′. From there, the gas can be removed to the factory exhaust and to a scrubber.

After processing, at a sixth action1060, the support pedestal106is lowered by the pedestal motor209to a location just above the location when the bases of the support pins will contact the base of the module body102a. At a seventh action1070the catch ring is moved up so that the upper surface216of the edge ring202is just above the top of the inner wall230of the ring185, and below the upper end wall of the outer wall232as shown inFIG. 2. The support pedestal106is then rotated by the pedestal rotation motor207at an eighth action1080to an angular velocity sufficient to accelerate the fluid off of the substrate150and into the trough236of the catch ring185, where it may flow into the reservoir121through the catch ring drain186connected to the trough236. During this rotation, at a ninth action1090the spray arm moves over the substrate150and sprays DI water through a second opening191bthereof to help flush off the fluid from the substrate150. At this point, at a tenth action1100, this secondary rinse fluid is accelerated off of the substrate150by rotation of the support pedestal106by the pedestal rotation motor207. The pedestal106is then lowered by the pedestal motor242to engage the substrate150with the support pins252at an eleventh action1110when the support pins252contact base of the module body102and remain so engaged to support the substrate150while the pedestal106continues to be lowered by the pedestal motor242. At this support position, the robot blade250enters through the port193and is extended under the supported substrate150to lift it off the support pins252. At a twelfth action the robot blade250with the substrate150retracts toward the chamber wall189, and removes the substrate150through the chamber port193. At this point these actions can be repeated to process another substrate150within the module body. In an additional embodiment, the chambers100may be stacked incorporated into a post exposure process module406as is shown inFIGS. 12 and 13. InFIG. 12, a modular lithography system400if shown schematically, which includes a pre exposure module404configured to house the chambers required to deposit a resist layer on a substrate150and prepare that resist layer to be exposed to electromagnetic energy, a photolithography module402configured to expose the resist layer to electromagnetic energy, and a post exposure module406configured to perform post exposure bake of the substrates in a field guided post exposure bake chamber100, and then develop the resist in a developer chamber408.

As shown inFIG. 13, the post exposure module includes a plurality of field guided post exposure bake chambers100, and developing chambers408stacked therein. Here, each post exposure bake chamber100can share a common fluid reservoir, vacuum source, and nitrogen source and the supply plumbing between these resources and the individual field guided post exposure bake chambers100. In addition, the chamber exhaust is connected to a common line leading to the factory exhaust. As shown inFIG. 13, for example, two columns or stacks of field guided post exposure bake chambers100stacked one over the other, and two columns or stacks of developer chambers408stacked one over the other, are provided. The number of stacks, and the number of chambers in each stack, are determined by the number of substrates that need to be simultaneously processed to perform post exposure bake and developing thereof, based on the throughput of the lithographic exposure module404. An atmospheric robot412is provided to retrieve substrates150from the lithographic exposure module404and pace the substrate into an idle post exposure bake chamber100, and after post exposure baking is completed, move the substrate150to a developing chamber408. Thereafter, the robot retrieves the substrate from the developer chamber408, and moves it to a factory interface410for placement into a FOUP or other substrate transfer device (not shown).

The robot412includes an upright open body416supporting an elevation mechanism418for vertically moving a blade support plate414. The open body416is horizontally moveable on an elevator418. Moving the open body on the track positions the robot blades250a, bon the blade support plate414in alignment with one of the stacks of chambers102,408. Vertical movement of the blade support plate414positions the robot blades250a, bto access the interior of a post exposure bake chamber102through the port193thereof. Two robot blades250a, bare provided, so that one blade contacts the substrate after heating thereof in the post exposure bake chambers100, whereas the other contracts a substrate before the heating thereof. Motors on the blade support plate414move the robot blades250a, b, also know and end effectors, inwardly and outwardly of the chambers100,408, and the elevator418also provides the horizontal motion to lift or lower a substrate with respect to the substrate support pins.