Patent Application
20080105201
Embodiments of the present invention relate to substrate support components used to support or transport a substrate in a process chamber.
Electronic circuits of CPUs, displays and memories, are fabricated on a substrate in a process chamber by forming materials and layers on the substrate, and selectively etching the layers to form features. The substrates typically include semiconductor wafers and dielectrics. The substrate materials are deposited or formed by processes such as chemical vapor deposition (CVD), physical vapor deposition (PVD), oxidation, nitridation and ion implantation. The substrate materials are then etched to define electrical circuit lines, vias, and other features on the substrate. A typical process chamber has enclosure walls that enclose a substrate support, gas distributor and exhaust port, and can also include a gas energizer to energize process gas in the chamber by high frequency (RF) or microwave energy.
In a typical process cycle, the contact surfaces of different support components touch or contact the substrate. For example, a substrate is transported by a support component such as a transport blade operated by a robot arm from a substrate stack in a cassette in a load-lock chamber to a process chamber and vice versa. In the chamber, the blade places the substrate on a support component comprising a set of lift pins which are extended though holes in a substrate support, and then withdraws from the chamber. The lift pins retract into the substrate support to rest the substrate upon the receiving surface of the support. The substrate support can include a pedestal, a vacuum chuck having a vacuum port to suck down the substrate, or an electrostatic chuck comprising a dielectric covering an electrode to which a voltage is applied to generate an electrostatic force to hold the substrate.
The contact surfaces of the support components that contact the substrate often contaminate the substrate surface with contaminant particulates. For example, stainless steel surfaces of a pedestal leave behind trace amounts of iron, chromium or copper on the backside surfaces of the substrate. Nickel coated robotic blades can also contaminate the substrate with residual nickel particles. Similarly, aluminum robot blades can leave behind aluminum particulates on the substrate. Although the particulate contaminants are often deposited on the inactive backside surface of the substrate, they can diffuse to the active front side in high temperature processes causing failure of the circuits and displays formed on the substrate. The particulate contaminants can also flake off from the substrate and fall upon and contaminate other substrates to reduce the effective yields from the substrates.
Contaminant particles can also arise from the substrate itseIf due to abrasion of the backside or peripheral edge of the substrate when the substrate rubs against the support components, for example, during transportation of the substrate by robot blade or lifting up of the substrate by lift pins. Abrasion of the backside or edge of the substrate is particularly a problem when the support component has a surface which has a high hardness, for example, in diamond-like coating as taught in aforementioned U.S. patent application Ser. No. 10/786,876, entitled “Coating for Reducing Contamination of Substrates During Processing” to Parkhe et al., assigned to Applied Materials, Inc. and filed on Feb. 24, 2004, which is incorporated by reference herein in its entirety. The harder surface abrades the substrate to generate contaminant microparticles which remain on the support surface or stick to the substrate. However, if the component has a surface which is too soft, it is easily upgraded by the substrate which also creates contaminant particles that originate from the component material.
As the features formed on the substrates transition to smaller than 90 or even 45 nm, the defects caused by contaminant particles have an increasing effect in reducing substrate yields in the manufacturing process. Transitioning to smaller features sizes and geometries means smaller sized defects impact product yields, which in turn, have a larger effect on the overall cost structure of manufacturing the IC chips and displays.
Thus it is desirable to reduce contamination of the substrate by contaminant particles, increase substrate yields, and obtain better process efficiency. It is further desirable to have substrate support component that does not excessively abrade a substrate during its use. It is also desirable for the support surface to be resistant to abrasion by the substrate itself.
The features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings, which illustrate examples of the invention. However, it is to be understood that each of the features can be used in the invention in general, not merely in the context of the particular drawings, and the invention includes any combination of these features, where:
An embodiment of a substrate processing apparatus 100 suitable for processing substrates 104 is shown in
During processing, one substrate 104 at a time is transported or held by a support component 120 between or in the chambers 110a-j. The support components 120 includes transport and supporting components used to transfer a substrate 104 from a cassette 116 to a chamber 110a-d, from one chamber 110 to another chamber, lift and lower the substrate 104 in a chamber 110, and hold a substrate 104 during processing in a chamber. It should be understood that the exemplary embodiments of support components 120 that are described herein are provided to illustrate the present invention, and should not be used to limit the scope of the present invention, and that other versions of support components apparent to those of ordinary skill are also within the scope of the present invention.
The support components 120 have a quartz contact tip 124 that reduces the formation of contaminant particles from the substrate 104 or the component 120 itself to significantly improve the yields of integrated circuit chips and displays from the processed substrates 104. The quartz contact tip 124 forms at least a portion of the support surface 126 of the support structure 128 of the support component 120. The area of contact provided by the quartz contact tip 124 forms is smaller than the area of the support surface 126 to reduce contact and thus, contamination of the substrate 104.
It has been determined that the contaminant particles can be generated from the substrate 104 itself when the frictional and abrasive forces between the component 120 and the substrate 104 abrade the substrate or component. Such contamination is especially a problem when the component 120 is made from a material having a higher Mohr's hardness that the hardness of the material forming the backside of the substrate 104. Abrasive forces also create particles when the support surface is too soft because this surface itself is then abraded by the higher hardness of the backside of the substrate 104.
It is believed that the quartz contact tip 124 reduces contamination because it has the desired range of hardness values suitable supporting and transporting a substrate 104 made from a silicon or silicon oxide. The quartz contact tip 124 comprises a crystalline form of silicon dioxide which has a hexagonal crystal structure. The quartz contact tip 124 has a Mohr hardness of about 7 which has been determined to reduce abrasion of silicon wafers and glass panels. At the same time, the quartz contact tip 124 is sufficiently soft so as not to abrade the silicon wafer or display itself. The hardness of the quartz contact tip 124 can be measured by, for example, a hardness load and displacement indentation test. A suitable instrument for performing the hardness test can be a “Nano Indenter II” available from Nano Instruments, Inc. in Oak Ridge, Tenn. In this test, the tip of an indenter probe is placed against the quartz contact tip 124, and a load is applied to the indenter probe to press the tip into the surface 124 to form an indentation in the surface 124. The tip of the indenter probe can be, for example, pyramidal shaped, and a suitable load may be in the microgram range. The hardness of the surface 124 can be found by evaluating the indentation, for example, by taking a ratio of the force applied to the indenter probe divided by the area of the indentation that results from the force, as described for example in Review of Instrumented Indentation in the Journal of Research of the National Institute of Standards and Technology, Vol. 108, No. 4, July-August 2003, which is herein incorporated by reference in its entirety. The area of the indentation can be calculated, for example, optically or by monitoring a depth of the indenter probe in the surface 124 and using a known geometry of the tip of the indenter probe.
The quartz contact tip 124 also has a relatively low coefficient of friction which reduces the frictional forces between the substrate and coating which leads to lower abrasion of these surfaces. The quartz contact tip 124 can even have a coefficient of friction of less than about 0.3. The quartz contact tip 124 can also be polished to provide a coefficient of friction of less than about 0.2, and an average surface roughness of less than about 0.4 micrometers.
The quartz contact tip 124 can be fabricated in a crystalline solid form or deposited as coating to have a low level of metallic impurities such as Fe, Cr, Ni, Co, Ti, W, Zn, Cu, Mn, Al, Na, Ca, K and B. The metallic impurities rub off upon, and migrate from, the surfaces of the support components and into the substrates causing shorts in the substrate circuitry. Suitable quartz contact tip 124 have a metal concentration level of less than about 5×1012 atoms/cm2 of metal atoms at the surface 124 of the coating, or even less than about 5×1010 atoms/cm2 of metal atoms.
Thus the quartz contact tip 124 of the support component 120 provides the desirable range of hardness, good frictional properties, and/or low-levels of contaminants. The quartz contact tip 124 covers at least a portion of the support surface 126 of a support structure 128 or may cover substantially the entire surface in contact with the substrate 104. The quartz contact tip 124 is also sufficiently thick to protect the substrate 104 from contamination by the underlying support structure 128, for example the quartz contact tip 124 may comprise a thickness of at least about 1 mm, such as from about 2 to about 6 mm or even from about 3.8 to about 4.1 mm. In one version, for example, the quartz contact tip 124 has a measured thickness of from about 3.835 mm to about 4.089 mm.
As one example, the substrate transfer chamber 116a on the platform contains a support component 120 comprising a robot 118 to transfer substrates 104 from the cassette 115 to the different chambers 110a-d for processing and return them after processing. In one embodiment, the robot 118 has a robot blade 130 capable of lifting and transferring a substrate 104 from the transfer chamber 116 and into and out of the chambers 110a-d through a slit 134 in the chamber as shown in
A plurality of raised mesas 160 extend out from the plate 136 of the robot blade 130. The mesas 160 are arranged on the support surface 126 of the support structure 128 of the support component 120 comprising the robot blade 130. The raised mesas 160 each have a quartz contact tip 124 that contacts the substrate 104 when the substrate is lifted by the blade 130. The quartz contact tips 124 present a much smaller area than the entire support surface 126 of the plate 136, and thus, minimize contact of the backside of a substrate 104 with the rest of the robot blade 130 resulting in less contamination of a substrate 104 during its transportation. The mesas 160 are also positioned within or inside the perimeter edge (not shown) of the backside of a substrate 104 that is confined by the opposing arcuate inner edges 158a,b of the arcuate ridges 148a,b and the arcuate ledge 154, respectively. The substrate 104 rests on the raised mesas 160 at its inner backside surface to minimize contact with the perimeter edge of the substrate 104 which typically has residual backside deposits. For example, the raised mesa 160 can be arranged to contact the backside of the substrate 104 within a substrate diameter that is at least about 4 mm inside the perimeter edge of the substrate 104 to reduce cross contamination of substrates 104 during their transfer in and out of a process chamber 110. The raised mesas 160 have a height of at least about 1 mm or even at least about 2 mm and are typically sized from about 3 to about 25 mm or even from about 8.6 to about 20 mm. Thus the quartz contact tip 124, which also have a thickness, have a height of from about 1.6 mm to about 2.4 mm above the surface of the plate 136. In one version the thickness of the quartz contact tip 124 is measured to be from about 1.930 mm to about 2.184 mm.
In another version, the support component 120 comprises a heat exchange pedestal 170, which is typically located in a heat exchange chamber 110h,j, an embodiment of which (110h), is shown in
The body 176 of the pedestal 170 comprises one or more conduits 178 provided for the passage of a heat exchanging fluid from a fluid source 179 through the body 176. The conduits 170 can be spiral tube that spirals inward, a doubled over tube that traverses across the pedestal 170, or other conventional configurations. In one version, the heat exchanging chamber 110h is a cooling chamber, and in use, a cooled fluid is passed through the conduits 178 of the heat exchange pedestal 170 to cool the substrate 104. The heat exchange pedestal 170 when operated as a cooling pedestal is capable of cooling the substrate 104 to a temperature of less than about 80° C. The heat exchange pedestal 170 can also be a heating pedestal having the same structure but with a heating fluid, i.e, a fluid heated to a temperature passed through the conduit 178 to heat the overlying substrate 104.
The heat exchange chamber 110h comprises an enclosure wall 180. During cooling, a cooling or heating gas can also be passed into the chamber 110 through a gas distributor 184 that includes a gas supply 186 and at least one gas inlet 188 feeding the chamber 110h. An exhaust 190 includes an exhaust port 192 that receives the cooling gas from the chamber and pumps out the same with an exhaust pump (not shown). A controller 194 comprising computing hardware and software can be used to control the chamber components, including the heat exchange pedestal 170 and the temperature and flow rate of the fluid passed through the conduits 178 of the pedestal 170, as well as the gas introduced into the chamber thorough the gas inlet 188.
The heat exchange pedestal 170 further comprises a plurality of holes 200 arranged about the receiving surface 172 of the body 176, as shown in
In one version, the holes 200 and quartz pieces 208 therein, are arranged a distance d away from a perimeter 210 of the receiving surface 172 of the body 176. The distance d is selected to be a sufficiently large distance to avoid contact of the backside perimeter edge of the substrate 104 which typically has residual backside deposits thereon, with the quartz contact tip 124 of the quartz pieces 208. For example, the quartz pieces 208 and holes 200 can be arranged to contact the backside of the substrate 104 within a substrate diameter that is at least about 4 mm from the perimeter edge of the substrate 104. This avoids contamination of the quartz contact tips 24 with the residual backside contaminants of the substrate 104.
Another embodiment of a removable assembly 212 comprising a quartz piece 208 in a hole 200 in a heat exchange pedestal 170 is shown in
The support components 120 further comprise lift pins 240 which are extended out of the pedestal 170 to receive a substrate 104 transported into the chamber 110h by the robot blade 130, as shown in
The lift pins 160 are part of a lift pin assembly 250 which includes a lift pin support 254 that holds the lift pins 240 and that is attached to a movable post 258 to raise and lower the lift pins 240 as shown in
In yet another version, the support component 120 comprises a substrate lifting fin assembly 285, an exemplary version of which is shown in
A first pair of arcuate fins 290a,b are mounted at one portion 292a of the circular hoop 286, and a second pair of arcuate fins 290c,d are mounted at another portion 292b of the hoop 286 which is in an opposing or facing arrangement. The arcuate fins are mounted on the flat walls 302a,b which in turn are mounted on the circular hoop 286. Each of the arcuate fins 290 comprises two ends 294a,b that each have a step-down ledge 298a,b that extends radially inward toward the pedestal 170. The second pair of arcuate fins 290c,d are mounted below the first pair of arcuate fins 290a,b to allow the simultaneous transport of more than one substrate 104. In one version, the arcuate fins 290a-d are composed of a metal, such as for example stainless steel or aluminum.
The step-down ledges 298 on each opposing end 294a,b of the arcuate fins 290 cooperate to form a lifting structure capable of lifting a substrate 104 off, and onto, the pedestal 170 by setting the substrate 104 on the ledges 190. The step-down ledges 298a,b may be connected to the opposing ends 294a,b by a beveled connecting region 306 that slopes downwardly from each end 294a,b to the step-down ledge 298a. The step-down ledges 298a,b are desirably sized to suitably support the substrate 104, and may also extend inwardly a sufficient distance to support the substrate 104 without excessive contact or rubbing between the beveled connecting region 306 and the substrate 104, thereby reducing the contamination of the substrate 104. For example, to lift and transport a substrate 104 having a diameter of about 300 mm, the ledges 298a,b may extend inwardly from the opposing ends 294a,b by at least about 7 mm.
Each step-down ledges 298a comprises a raised protrusion 300 having a quartz contact tip 124, as shown in
The raised protrusion 300 are also located inward from the perimeter 315 of the ledge 298a, such that the quartz contact tip 124 of the raised protrusion 300 contacts the substrate 104 at regions away from the perimeter edge of the backside of the substrate 104, which are typically less contaminated than the perimeter edge portion. For example, the raised protrusion 300 may be spaced away from the perimeter such that they contact the substrate at a diameter that is at least about 4 mm inside the perimeter of the substrate 104, and even at least about 7 mm inside the perimeter. A suitable height of the raised protrusions 300 to minimize contact of the substrate 104 with the surface 310 of the step-down ledge 298 can be a height of at least about 1 mm, such as from about 1 mm to about 2 mm, and even at least about 1.5 mm.
Although exemplary embodiments of the present invention are shown and described, those of ordinary skill in the art may devise other embodiments which incorporate the present invention, and which are also within the scope of the present invention. For example, the robot blade 130, heat exchange pedestal 170, lift pins 240, or other support components 120 may comprise other shapes and configurations other than those described herein. Furthermore, relative or positional terms shown with respect to the exemplary embodiments are interchangeable. Therefore, the appended claims should not be limited to the descriptions of the preferred versions, materials, or spatial arrangements described herein to illustrate the invention.
This application claims priority to U.S. Provisional Application Ser. No. 60/864,286, filed Nov. 3, 2006, which is incorporated herein by reference and in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60864286 | Nov 2006 | US |
