Substrate transfer robot end effector

Embodiments of apparatus for supporting a substrate are disclosed herein. In some embodiments, an apparatus for supporting a substrate includes a support member; and a plurality of substrate contact elements protruding from the support member, wherein each of the plurality of substrate contact elements includes: a first contact surface to support a substrate when placed thereon; and a second contact surface extending from the first contact surface, wherein the second contact surface is adjacent a periphery of the substrate to prevent radial movement of the substrate, wherein the first contact surface is at a first angle with respect to the support member and the second contact surface is at a second angle with respect to the support member, and wherein the first angle is between about 3 degrees and 5 degrees.

FIELD

Embodiments of the present disclosure generally relate to semiconductor processing equipment.

BACKGROUND

In the fabrication of microelectronic devices on semiconductor substrates, the semiconductor substrate is handled on its edge and backside numerous times during the manufacturing process. Such handling can cause contaminants to adhere to the backside of the substrate and travel between processing components, for example, from chamber to chamber, FOUP (front opening unified pod) to FOUP, or process tool to process tool along with the substrate, or between different substrates, undesirably increasing tool downtime for maintenance to remove the contaminants. These contaminants can also migrate to the front side of the substrate, resulting in reduced device performance and/or yield loss.

Typical solutions to this problem have been to reduce the backside particle generation by reducing a contact area between the substrate and substrate transferring/handling devices. However, while this solution mitigates particle generation, the inventors have observed that large numbers of particles are still generated even with the smallest contact areas contemplated.

As such, the inventors have provided embodiments of improved apparatus for supporting and handling a substrate with reduced particle generation.

SUMMARY

Embodiments of apparatus for supporting a substrate are disclosed herein. In some embodiments, an apparatus for supporting a substrate includes a support member; and a plurality of substrate contact elements protruding from the support member, wherein each of the plurality of substrate contact elements includes: a first contact surface to support a substrate when placed thereon; and a second contact surface extending from the first contact surface, wherein the second contact surface is adjacent a periphery of the substrate to prevent radial movement of the substrate, wherein the first contact surface is at a first angle with respect to the support member and the second contact surface is at a second angle with respect to the support member, and wherein the first angle is between about 3 degrees and 5 degrees.

In some embodiments, a substrate transfer robot for transferring a substrate includes an arm including a blade; and a plurality of substrate contact elements protruding from an upper surface of the blade. Each of the plurality of substrate contact elements includes a first contact surface to support a substrate when placed thereon; and a second contact surface extending from the first contact surface, wherein the second contact surface is adjacent a periphery of the substrate to prevent radial movement of the substrate, wherein the first contact surface is at a first angle with respect to the upper surface and the second contact surface is at a second angle with respect to the upper surface, and wherein the first angle is between about 3 degrees and 5 degrees.

In some embodiments, a substrate transfer robot for transferring a substrate includes an arm including a blade, wherein the blade is formed of an electrically conductive titanium-doped ceramic; and a plurality of substrate contact elements protruding from an upper surface of the blade. Each of the plurality of substrate contact elements includes a first contact surface to support a substrate when placed thereon; and a second contact surface extending from the first contact surface, wherein the second contact surface is adjacent a periphery of the substrate to prevent radial movement of the substrate, wherein the first contact surface is at a first angle with respect to the upper surface and the second contact surface is at a second angle with respect to the upper surface, wherein the second angle is greater than the first angle; and wherein the first angle is between about 3 degrees and 5 degrees.

DETAILED DESCRIPTION

Embodiments of the present disclosure provide improved substrate handling apparatus that provides reduced particle generation as compared to conventional substrate supporting apparatus. Embodiments of the present disclosure may advantageously avoid or reduce contamination accumulated on a substrate during the manufacturing process, such as while handling the substrate between process steps, which can further limit or prevent contaminants from reaching the front-side of a substrate and causing device performance issues and/or yield loss. Embodiments of the present disclosure may be used in a wide variety of surfaces that contact a substrate in processes where very low addition of particles is desired, for example, in display processing, silicon wafer processing, optics manufacturing, and the like.

FIG. 1depicts a substrate transfer robot100according to some embodiments of the present disclosure. For example, a substrate transfer robot100may comprise a robot arm (arm104) for vertical and rotational displacement at a first end106. The arm104may comprise one or more links, for example first link108and second link110pinned together at axis112. A second end114of the arm104may include a wrist116to which the first end of a blade102is coupled. The blade102may include contact pads118protruding from an upper surface of the blade to support a substrate. The contact pads118are described in more detail below with respect toFIGS. 2 through 6.

In operation, the substrate transfer robot100may be controlled such that the blade102is positioned below a substrate150supported on a plurality of lift pins120. Through manipulation of the substrate transfer robot100and the arm104, the blade102is raised from a position below the substrate150to bring the contact pads118into contact with at least one of the edge or back side of the substrate150and to lift the substrate150off of the lift pins120. When contacting the substrate150, particles are often generated at the contact area between the contact pads118and the substrate150.

The inventors have discovered that particles are generated when the material of any element that contacts the substrate is harder than the substrate material (e.g., silicon), has a high adhesion to the substrate material, cannot prevent the substrate from sliding, has a rough surface, and is not conductive. For example, if a substrate is initially contacted by an element formed of a sticky material and is later contacted by another element formed of a hard material, the generation of particles on the substrate is exacerbated. Similarly, if there is current flow between the substrate and a conductive material and the substrate is lifted by a non-conductive material, arcing may occur, exacerbating the generation of particles on the substrate.

The inventors have discovered that particle generation can be prevented or substantially minimized by using a material exhibiting a predetermined set of properties in elements that contact the substrate (e.g., contact pads118). The predetermined set of properties includes: a hardness less than or equal to that of a substrate to be supported (e.g., silicon), non-adhesiveness, a coefficient of static friction high enough to prevent sliding of the substrate on elements that contact the substrate, electrically conductive, and a surface roughness less than or equal to 10 Ra. Such a material may include, for example, one or more of aluminum oxide, silicon nitride, stainless steel, and electrically conductive plastics, such as Kapton®, Kalrez®, Vespel®, and Celazole®. Other process-compatible materials exhibiting the above-noted properties may be used.

Conventional edge contact pads include an edge support surface at a steep angle with respect to a horizontal plane (approximately 60 degrees). The inventors have discovered that upon lifting a substrate, the substrate slides into its final resting position because of the steepness of edge support surface angle. This sliding causes particle generation on the edge of the substrate. Therefore, the inventors have discovered that particle generation can be prevented or substantially minimized by providing edge contact pads with a shallow incline.

For example,FIG. 2depicts an end effector202in accordance with some embodiments of the present disclosure. The end effector202includes a plurality of edge contact pads210(four shown inFIG. 2) which are coupled to a support member204. The edge contact pads210can be used as the contact pads118depicted inFIG. 1. In some embodiments, the support member204is substantially planar, or includes a substantially planar region sufficient to support a substrate. In some embodiments, the support member204is formed of a ceramic material and may be doped with titanium. The titanium doped ceramic material is advantageously provides more resistance to droop as compared to conventional substrate transfer robot blades. In addition, the titanium doped ceramic support member is advantageously electrically conductive. The end effector202may also include a feature206, such as a hole, which may be used to for substrate alignment purposes and/or weight reduction of the end effector202. A distance L between front and back edge contact pads210is slightly larger than a diameter of a substrate being processed. For example, the distance L may be about 304 mm for handling substrates having a 300 mm diameter. However, the distance L will depend upon the size of the substrate being handled.

FIG. 3depicts a side view of an edge contact pad210in accordance with some embodiments of the present disclosure. The edge contact pad210includes a first contact surface302and a second contact surface304. The first contact surface302is at a first angle θ with respect to the support member204. The second contact surface304is at a second angle α with respect to the support member204. Due to the weight of the substrate150and inertial forces caused by movement of the substrate150by the substrate transfer robot100, each edge contact pad210imparts a normal (frictional) force and a radial force on the substrate. The radial force is directed towards a center of the substrate150to ensure that it remains stationary. In order to ensure a sufficient magnitude of frictional and radial forces on the substrate, the first angle θ may be between about 3 degrees and 5 degrees. The first angle θ is small enough to ensure that a radial force directed towards a center of the substrate exists while maintaining sufficient frictional forces to prevent sliding of the substrate. A horizontal length of the first contact surface302may be between about 4 mm to about 7 mm, preferably about 5.8 mm. The second angle α is larger than the first angle θ so that the second contact surface304is substantially vertical. The second contact surface304acts as a bumper in case the substrate slides during placement.

The edge contact pad210is coupled to the support member204of the end effector202. In some embodiments, one or more screws306may be used to couple the edge contact pad210to the support member204. The screws306include a through hole to ensure evacuation of any air pockets between the screw306and the edge contact pad210. In some embodiments, one or more shims308may be used to control the height of the edge contact pad210above the support member204, thus advantageously ensuring that the substrate is correctly leveled on all of edge contact pads.

FIG. 4depicts a perspective view of an edge contact pad210in accordance with some embodiments of the present disclosure. The edge contact pad210depicted inFIG. 4is similar to the edge contact pad210shown inFIG. 3except that the edge contact pad210inFIG. 4includes a first contact surface402and a second contact surface404that are curved (as compared to the linear surfaces shown inFIG. 3). The inventors have discovered that by providing a curved contact surface, the frictional and radial forces applied to the substrate vary depending on the position of the substrate. As such, if the substrate slides, the radial forces acting on the substrate increase or decrease depending upon the position of the substrate with respect to the edge contact pad210. For example, the radial forces will be higher where the substrate is at a higher angle and lower where the substrate is at a lower angle. As a result, further sliding of the substrate in a particular direction is limited or prevented. An angle θ between the first and second contact surfaces402,404and the horizontal plane varies from at or near 0 degrees at the beginning of the first contact surface402to at or near 90 degrees at the end of the second contact surface404. The first contact surface402(e.g., the portion of the curved surface at lesser angles and more radially inward) functions as a support surface for a substrate placed thereon and the second contact surface (e.g., the portion of the curved surface at greater angles and more radially outward) functions as a bumper to prevent sliding of the substrate. The first and second contact surfaces402,404form a continuous curved surface. Alternatively, a combination of curved an linear surfaces may be used providing shallower angles to support the substrate and greater angles to prevent further movement of the substrate in case of slippage.

FIG. 5depicts an end effector500in accordance with some embodiments of the present disclosure. The end effector500includes backside contact pads510coupled to a support member502of the end effector500to support a substrate by the backside of the substrate, rather than the edges as described above with respect toFIGS. 2-4. The backside contact pads510can be used as the contact pads118depicted inFIG. 1. When the substrate transfer robot lifts the substrate150off of the lift pins120, the substrate150is accelerated from a velocity of zero to a transfer speed. The acceleration results in a force F at contact areas corresponding to the locations of the contact pads118, as illustrated inFIG. 6. As a result, particles are generated at the contact area between the backside contact pads510and the substrate150.

Similar to the edge contact pads210,210, the backside contact pads510may be coupled to the support member502of the end effector500using screws506. The screws506may be vented to facilitate venting of any air gap between the screw and the backside contact pad510. Although not shown, shims similar to those depicted inFIGS. 3 and 4may be used to raise any of the backside contact pads510to ensure proper leveling of the substrate150when placed thereon.

Thus, improved apparatus and materials for avoiding particle generation on a substrate have been disclosed herein. The inventive apparatus may advantageously allow for the reduction or prevention of contamination accumulated on a substrate during the manufacturing process, such as during handling the substrate between process steps and while supporting the substrate inside a process chamber, thus preventing or reducing the incidence of contaminants from reaching the front-side of a substrate and causing reduced device performance and/or yield loss.