Patent Description:
The following document is cited as a relevant prior art illustration:
Document <CIT> discloses a radially oscillating carousel processing system for chemical mechanical polishing. Said system includes an apparatus for polishing semiconductor wafers and other workpieces, and also includes a polishing pads mounted on respective platens at multiple polishing stations.

The following documents are also mentioned as a complementary prior art illustration:.

The field of the disclosure relates to processing semiconductor substrates and, in particular, methods and systems for automated semiconductor wafer polishing and cleaning.

Semiconductor wafers are commonly used in the production of integrated circuit (IC) chips on which circuitry are printed. The circuitry is first printed in miniaturized form onto surfaces of the wafers. The wafers are then broken into circuit chips. This miniaturized circuitry requires that front and back surfaces of each wafer be extremely flat and substantially free of defects to ensure that the circuitry can be properly printed over the entire surface of the wafer. To accomplish this, polishing processes are commonly used to improve flatness of the front and back surfaces of the wafer after the wafer is cut from an ingot. A particularly good, defect free finish is required when polishing the wafer in preparation for printing the miniaturized circuits on the wafer by an electron beam-lithographic or photolithographic process (hereinafter "lithography").

Once the wafer has been polished, the wafer is cleaned in a wet bath to remove any debris generated during polishing. Typically, the wafer is transferred from the polisher to the wet bath manually using vacuum pencils to hold the wafers during transfer. That is, an operator typically picks up the wafer with the vacuum pencil and places the wafer in the wet bath. Automating the transfer process would increase the efficiency of the wafer manufacturing process and decrease production costs. However, the robots that typically transfer wafers in manufacturing facilities and the wet baths that typically clean the wafers are not designed for the precision handling required to safely place the wafers in the wet bath without scratching or otherwise damaging the wafers during the transfer process.

This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the disclosure, which are described and/or claimed below.

One aspect of the present disclosure is directed to a semiconductor wafer processing system for processing a set of semiconductor wafers. The system includes a controller, a transfer robot controlled by the controller, a wet bath for containing a cleaning solution, and a cassette positioned in the wet bath for holding the set of wafers. The transfer robot transfers the wafer from a transfer location to the cassette and the controller controls the transfer robot during the transfer.

Another aspect of the present disclosure is directed to a wafer processing system for processing a wafer. The system includes a transfer robot, a wet bath, a cassette, an automated guided vehicle (AGV), and a cassette holder. The wet bath includes a wall and defines a container for retaining a cleaning solution. The cassette is positioned within the wet bath for holding the wafer. The transfer robot transfers the wafer from a transfer location to the cassette. The AGV includes a robot arm for positioning the cassette in the wet bath and removing the cassette from the wet bath. The cassette holder is attached to the wall for maintaining a position of the cassette within the wet bath. The AGV positions the cassette within the cassette holder and removes the cassette from the cassette holder.

Yet another aspect of the present disclosure is directed to a method of processing a wafer. The method includes positioning a cassette within a wet bath with an automated guided vehicle (AGV). The method also includes transferring the wafer from a transfer location to the cassette with a transfer robot. The method further includes removing the cassette and the wafer from the wet bath with the AGV.

Various refinements exist of the features noted in relation to the above-mentioned aspects of the present disclosure. Further features may also be incorporated in the above-mentioned aspects of the present disclosure as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated embodiments of the present disclosure may be incorporated into any of the above-described aspects of the present disclosure, alone or in any combination.

Although specific features of various examples may be shown in some drawings and not in others, this is for convenience only. Any feature of any drawing may be referenced and/or claimed in combination with any feature of any other drawing.

Unless otherwise indicated, the drawings are meant to illustrate features of examples of the disclosure. These features are believed to be applicable in a variety of systems comprising one or more examples of the disclosure. The drawings are not meant to include all conventional features known by those of ordinary skill in the art to be required for the practice of the disclosed examples disclosed.

Suitable substrates (which may be referred to as semiconductor or silicon "wafers") include single crystal silicon substrates including substrates obtained by slicing the wafers from ingots formed by the Czochralski process. Each substrate includes a central axis, a front surface, and a back surface parallel to the front surface.

With reference to <FIG>, a semiconductor wafer processing system <NUM> includes a polisher <NUM>, an unloading robot <NUM>, a transfer location <NUM>, a transfer robot <NUM>, a wet bath <NUM> including a cassette <NUM>, an automated guided vehicle (AGV) <NUM>, and a controller <NUM>. The polisher <NUM> polishes a wafer <NUM>, the unloading robot <NUM> unloads the wafer from the polisher to the transfer location <NUM>, the transfer robot <NUM> transfers the wafers from the transfer location to the cassette <NUM> in the wet bath <NUM>, and the AGV <NUM> removes the cassette from the wet bath for further processing of the wafers after the wafers have been cleaned in the wet bath. The system <NUM> automates the unloading, loading, and cleaning processes by using robots <NUM>, <NUM>, and <NUM> to unload and load the wafers <NUM> and the controller <NUM> to control the robots. Accordingly, system <NUM> increases the efficiency of the overall wafer production process and decreases the overall cost to produce a wafer.

With reference to <FIG> and <FIG>, the polisher <NUM> is a double-side polisher that rough or finish polishes the wafer <NUM>. The rough and finish polish may be achieved by, for example, chemical-mechanical planarization (CMP). CMP typically involves the immersion of the wafer <NUM> in an abrasive slurry and polishing the wafer. Through a combination of chemical and mechanical action the surface of the wafer <NUM> is smoothed. Typically the polish is performed until a chemical and thermal steady state is achieved and until the wafers <NUM> have achieved their targeted shape and flatness.

The polisher <NUM> includes a first polishing assembly (not shown) and a second polishing assembly (lower polishing assembly) <NUM>. A first shaft (not shown) is attached to the first polishing assembly, and a second shaft (not shown) is attached to the second polishing assembly <NUM>. The wafer <NUM> is positioned between the first and second polishing assemblies, and the first and second shafts simultaneously rotate the first and second polishing assemblies, polishing the wafer.

With reference to <FIG>, the unloading robot <NUM>, transfer robot <NUM>, and AGV <NUM> each include a <NUM>-axis robot arm <NUM> including a base <NUM>, a first arm <NUM>, a base-first arm hinge <NUM>, a second arm <NUM>, a first arm-second arm hinge <NUM>, a tip <NUM>, and a second arm-tip hinge <NUM>. The base <NUM> supports the <NUM>-axis robot arm <NUM>, and the base-first arm hinge <NUM> movably attaches the base to the first arm <NUM>. The first arm-second arm hinge <NUM> movably attaches the first arm <NUM> to the second arm <NUM>, and the second arm-tip hinge <NUM> movably attaches the second arm <NUM> to the tip <NUM>.

Specifically, the base <NUM> rotates the first arm <NUM>, the second arm <NUM>, and the tip <NUM> about a first axis (generally indicated by arrow <NUM>). The base-first arm hinge <NUM> pivots the first arm <NUM> about a first pivot point <NUM>, defining a second axis (generally indicated by arrow <NUM>). The first arm-second arm hinge <NUM> pivots the second arm <NUM> about a second pivot point <NUM>, defining a third axis (generally indicated by arrow <NUM>) and rotates the second arm about a fourth axis (generally indicated by arrow <NUM>). The second arm-tip hinge <NUM> pivots the tip <NUM> about a third pivot point <NUM>, defining a fifth axis (generally indicated by arrow <NUM>) and rotates the tip about a sixth axis (generally indicated by arrow <NUM>).

With reference to <FIG> and <FIG>, the unloading robot <NUM> also includes a vacuum attachment <NUM> attached to the tip <NUM> for holding the wafer <NUM> during the transfer between the polisher <NUM> and the transfer location <NUM>. With reference to <FIG>, the transfer robot <NUM> also includes a wafer end effector <NUM> attached to the tip <NUM> for holding the wafer <NUM> during the transfer between the transfer location <NUM> and the wet bath <NUM>. With reference to <FIG>, the AGV <NUM> also includes a cassette transfer attachment <NUM> attached to the tip <NUM> for loading and unloading the cassette <NUM> from the wet bath <NUM>.

With reference to <FIG> and <FIG>, the transfer location <NUM> includes a wafer holder <NUM> for temporarily holding the wafer <NUM> during the transfer between the polisher <NUM> and the wet bath <NUM>. The wafer holder <NUM> includes prongs <NUM> for holding the wafer <NUM>. The wafer holder <NUM> is suitably made of aluminum, and the prongs <NUM> are suitably made of polyether ether ketone (PEEK) material. In the illustrated embodiment, the wafer holder <NUM> includes four prongs <NUM>. However, in alternative embodiments, the wafer holder <NUM> may include any number of prongs that enable the wafer holder to operate as described.

The wet bath <NUM> holds the cassette <NUM> and the wafers <NUM> and cleans the wafers <NUM>. With reference to <FIG>, the wet bath <NUM> includes a plurality of walls <NUM> that define a container <NUM> for retaining a cleaning solution. The wet bath <NUM> also includes at least one cassette holder <NUM>, at least one cassette stage guide <NUM>, a fluid trap <NUM>, and at least one AGV centering guide <NUM>. The cassette stage guide <NUM> and the AGV centering guide <NUM> assist the AGV <NUM> with positioning the cassette <NUM> in the wet bath <NUM>. The cassette holder <NUM> retains the cassette <NUM> in the wet bath <NUM>, the fluid trap <NUM> retains the cleaning solution in the container <NUM>, and the AGV <NUM> removes the cassette from the wet bath.

As illustrated in <FIG>, the cassette holder <NUM> is attached to two of the walls <NUM> of the wet bath <NUM> and includes a first holder <NUM> rotatably attached to a first wall <NUM> and a second holder <NUM> rotatably attached to a second wall <NUM> opposite the first wall. The first and second holders <NUM>, <NUM> each include a cassette latch <NUM> for engaging and retaining the cassette <NUM> and a plurality of extensions <NUM> for engaging and retaining the wafers <NUM>. The AGV <NUM> positions the cassette <NUM> in the wet bath <NUM>, and the first and second holders <NUM>, <NUM> rotate to engage the cassette latch <NUM> with the cassette <NUM> and the extensions <NUM> with the wafers <NUM>, retaining the cassette and the wafers in the wet bath during the cleaning process.

As shown in <FIG> and <FIG>, the cassette stage guide <NUM> is positioned on a bottom wall <NUM> of the container <NUM> and guides the cassette <NUM> into position as the AGV <NUM> loads the cassette into the wet bath <NUM>. The cassette stage guide <NUM> includes a guide base <NUM> and an angled guide <NUM> extending from the guide base. The guide base <NUM> is attached to the bottom wall <NUM>, and the angled guide <NUM> is attached to, and extends from, the guide base. The angled guide <NUM> is oriented at a first angle α1 relative to the bottom wall <NUM> and guides the cassette <NUM> to rest on the guide base <NUM> as the AGV <NUM> positions the cassette in the wet bath <NUM>.

With reference to <FIG>, the fluid trap <NUM> includes a platform <NUM> rotatably attached to at least one of the walls <NUM> at a trap pivot point <NUM>. Specifically, the platform <NUM> is attached to the wall <NUM> proximate to the AGV <NUM> and rotates about the trap pivot point <NUM> to catch and retain the cleaning solution that drips off of the cassette <NUM> as the cassette is unloaded from the wet bath <NUM> by the AGV. More specifically, the platform <NUM> rotates from a first or stored configuration <NUM> to a second or deployed configuration <NUM> when the AGV <NUM> unloads the cassette <NUM> from the wet bath <NUM>. The platform <NUM> is oriented at a second angle α2 relative to a surface <NUM> of the cleaning solution to channel cleaning solution back into the container <NUM>.

As shown in <FIG>, the AGV centering guide <NUM> includes a tubular guide <NUM> extending from the bottom wall <NUM> of the container <NUM> for guiding the cassette <NUM> onto the guide base <NUM> as the AGV <NUM> positions the cassette into the wet bath <NUM>. The tubular guide <NUM> includes a hollow tube defining a tube opening <NUM> for engaging and guiding the cassette <NUM> into the wet bath <NUM>. More specifically, as shown in <FIG>, the cassette transfer attachment <NUM> includes at least one centering rod <NUM> for guiding the cassette <NUM> onto the guide base <NUM> as the AGV <NUM> positions the cassette into the wet bath <NUM>. In the illustrated embodiment, the wet bath <NUM> includes two AGV centering guide <NUM> for each cassette <NUM>, and the cassette transfer attachment <NUM> includes two corresponding centering rods <NUM>. The centering rods <NUM> slide into the tube opening <NUM> as the AGV <NUM> lowers the cassette <NUM> into the wet bath <NUM>, positioning the cassette <NUM> onto the guide base <NUM>.

In this embodiment, the cleaning solution includes a non-abrasive fluid, such as deionized water, that is substantially free of silicon dioxide. More specifically, the cleaning solution includes deionized water. In alternative embodiments, the cleaning solution may include any fluid that enables the wet bath <NUM> to operate as described herein.

With reference to <FIG>, the cassette <NUM> includes a curved base <NUM> and two circular ends <NUM>. The curved base <NUM> includes a plurality of wafer slots <NUM> for retaining the wafers <NUM> and a plurality of engagement slots <NUM> for engaging with the cassette latches <NUM> of the first and second holders <NUM>, <NUM>. The transfer robot <NUM> positions the wafers <NUM> in the wafer slots <NUM> such that the wafers are retained in the wet bath <NUM>. After the AGV <NUM> positions the cassette <NUM> in the wet bath <NUM>, the first and second holders <NUM>, <NUM> are rotated such that the cassette latches <NUM> engage the engagement slots <NUM> and the extensions <NUM> are interdigitated between the wafers <NUM>, retaining the cassette and the wafers in the wet bath.

The controller <NUM> automatically controls each of the polisher <NUM>, the unloading robot <NUM>, the transfer robot <NUM>, the wet bath <NUM> including the first and second holders <NUM>, <NUM> and the fluid trap <NUM>, and the AGV <NUM>. Accordingly, the controller <NUM> automates the process of polishing the wafer <NUM>, transferring the wafer to the wet bath <NUM>, cleaning the wafer, and removing the cassette <NUM> including the wafer from the wet bath.

During operation, the wafer <NUM> is positioned between the first polishing assembly and the second polishing assembly <NUM>, and the polishing assemblies are rotated to polish the wafer. The unloading robot <NUM> removes the wafer <NUM> from the polisher <NUM> and positions the wafer on the wafer holder <NUM> at the transfer location <NUM>. Specifically, the unloading robot <NUM> positions the first and second arms <NUM> and <NUM> of the unloading robot such that the vacuum attachment <NUM> contacts the wafer <NUM>. The vacuum attachment <NUM> generates a suction that maintains the wafer <NUM> on the vacuum attachment while the unloading robot <NUM> transfers the wafer to the transfer location <NUM>. The controller <NUM> controls the unloading robot <NUM> during the transfer process such that the unloading robot transfers the wafer <NUM> automatically and without operator intervention.

The AGV <NUM> picks up the cassette <NUM> and positions the cassette in the wet bath <NUM>. Specifically, the AGV <NUM> attaches the cassette transfer attachment <NUM> to the cassette <NUM>, and the first and second arms <NUM> and <NUM> of the AGV <NUM> position the cassette above the wet bath <NUM>. The AGV <NUM> lowers the cassette <NUM> into the wet bath <NUM> such that the centering rods <NUM> slide into the tube openings <NUM> of the tubular guides <NUM> of the AGV centering guides <NUM>. The AGV centering guides <NUM> positions the cassette <NUM> in the wet bath <NUM> as the AGV <NUM> lowers the cassette into the wet bath. Additionally, the angled guide <NUM> of the cassette stage guide <NUM> also positions the cassette <NUM> in the wet bath <NUM> as the AGV <NUM> lowers the cassette into the wet bath. More specifically, the angled guide <NUM> engages the circular ends <NUM> of the cassette <NUM> to guide the cassette to the guide base <NUM> in the wet bath <NUM>. Together, the AGV centering guides <NUM> and the cassette stage guide <NUM> ensure that the AGV <NUM> positions the cassette <NUM>, which may include wafers <NUM>, in the wet bath <NUM> with enough precision to prevent scratches or damage to the wafers or the cassette. The cassette holders <NUM> are rotated after the AGV <NUM> positions the cassette <NUM> in the wet bath <NUM> such that the extensions <NUM> are interdigitated between the wafers <NUM> and the cassette latches <NUM> engage the engagement slots <NUM>. The cassette holders <NUM> maintain the position of the cassette <NUM> and the wafers <NUM> in the wet bath <NUM>. The controller <NUM> controls the AGV <NUM> during the transfer process such that the AGV transfers the cassette <NUM> automatically and without operator intervention.

The transfer robot <NUM> removes the wafer <NUM> from the transfer location <NUM> and positions the wafer in the wafer slots <NUM> of the cassette <NUM>. Specifically, the transfer robot <NUM> positions the first and second arms <NUM> and <NUM> of the transfer robot such that the wafer end effector <NUM> holds the wafer <NUM> while the transfer robot <NUM> transfers the wafer to the cassette <NUM>. The controller <NUM> controls the transfer robot <NUM> during the transfer process such that the transfer robot transfers the wafer <NUM> automatically and without operator intervention.

The wet bath <NUM> cleans the wafers <NUM> in the cassette <NUM>. After the wafers <NUM> have been cleaned, the platform <NUM> of the fluid trap <NUM> is rotated about the trap pivot point <NUM> from the first configuration <NUM> to the second configuration <NUM>. Additionally, the cassette holders <NUM> are rotated such that the extensions <NUM> are disengaged from the wafers <NUM>, the cassette latches <NUM> disengage from the engagement slots <NUM>, and the cassette holders no longer maintain the position of the cassette <NUM> in the wet bath <NUM>.

The AGV <NUM> picks up the cassette <NUM>, including the wafers <NUM>, and transfers the cassette and wafers downstream for further processing. Specifically, the AGV <NUM> attaches the cassette transfer attachment <NUM> to the cassette <NUM>, and the first and second arms <NUM> and <NUM> of the AGV <NUM> are actuated to remove the cassette from the wet bath <NUM>. The AGV <NUM> raises the cassette <NUM> out of the wet bath <NUM> such that the centering rods <NUM> slide out of the tube openings <NUM> of the tubular guides <NUM> of the AGV centering guides <NUM>. Additionally, the angled guide <NUM> of the cassette stage guide <NUM> guides the cassette <NUM> out of the wet bath <NUM> as the AGV <NUM> raises the cassette. More specifically, the angled guide <NUM> engages the circular ends <NUM> of the cassette <NUM> to guide the cassette off of the guide base <NUM>. Together, the AGV centering guides <NUM> and the cassette stage guide <NUM> ensure that the AGV <NUM> removes the cassette <NUM>, which includes cleaned wafers <NUM>, from the wet bath <NUM> with enough precision to prevent scratches or damage to the wafers or the cassette. The controller <NUM> controls the AGV <NUM> during the transfer process such that the AGV transfers the cassette <NUM> automatically and without operator intervention. The processing system <NUM> described herein automates the polishing, loading, unloading, and cleaning processes without damaging the wafers. Accordingly, the processing system <NUM> described herein increases the efficiency of the wafer production process and decreases the overall cost of manufacturing a wafer without damaging the wafers.

<FIG> is a method <NUM> of processing a wafer. The method <NUM> includes polishing <NUM> the wafer with the polisher. The method <NUM> also includes transferring <NUM> the wafer from the polisher to the transfer location with the unloading robot. The method <NUM> further includes positioning <NUM> the cassette within the wet bath with the AGV. Positioning <NUM> the cassette within the wet bath with the AGV may include centering <NUM> the cassette within the wet bath with the AGV centering guide and the centering rod. The method <NUM> also includes rotating <NUM> the cassette holder after the AGV positions the cassette within the wet bath such that the extensions are interdigitated between the wafers. The method <NUM> further includes maintaining <NUM> the position of the cassette within the wet bath with the cassette holder. The method <NUM> also includes transferring <NUM> the wafer from the transfer location to the cassette with the transfer robot. The method <NUM> further includes removing <NUM> the cassette and the wafer from the wet bath with the AGV.

Generally as disclosed herein, a semiconductor wafer processing system for processing a set of semiconductor wafers automatically loads each wafer into a wet bath for cleaning the wafers after the wafer have been polished. In an example, the system includes a polisher for polishing the wafers, an unloading robot for unloading the wafers from the polisher, a transfer robot for transferring the wafers into the wet bath, a cassette positioned in the wet bath for holding and transporting the wafers, and an automated guided vehicle (AGV) for positioning the cassette in the wet bath and removing the cassette from the wet bath. The system automatically polishes the wafers, automatically loads the wafers into the cassette and the wet bath for cleaning, and automatically unloads the cassette, including the wafers, for downstream processing. The unloading robot, transfer robot, and AGV automatically transport the wafers through the polishing and cleaning processes, automating the polishing and cleaning processes. The wet bath includes an AGV centering guide and a cassette stage guide to guide the cassette into and out of the wet bath with enough precision to prevent scratching or otherwise damaging the wafers during the transfer process. Automating the loading, unloading, and cleaning processes increases the efficiency of the wafer production process and decreases the overall cost of manufacturing a wafer without damaging the wafers.

As used herein, the terms "about," "substantially," "essentially" and "approximately" when used in conjunction with ranges of dimensions, concentrations, temperatures or other physical or chemical properties or characteristics is meant to cover variations that may exist in the upper and/or lower limits of the ranges of the properties or characteristics, including, for example, variations resulting from rounding, measurement methodology or other statistical variation.

When introducing elements of the present disclosure or the embodiment(s) thereof, the articles "a", "an", "the" and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," "containing" and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. The use of terms indicating a particular orientation (e.g., "top", "bottom", "side", etc.) is for convenience of description and does not require any particular orientation of the item described.

Claim 1:
A semiconductor wafer processing system (<NUM>) for processing a set of semiconductor wafers (<NUM>), the system comprising:
a controller (<NUM>);
a transfer robot (<NUM>) controlled by the controller;
a wet bath (<NUM>) for containing a cleaning solution;
a cassette (<NUM>) positioned in the wet bath for holding the set of wafers, wherein the transfer robot transfers the wafer from a transfer location (<NUM>) to the cassette and the controller controls the transfer robot during the transfer; and the semiconductor wafer processing system being characterized in that it further comprises:
an automated guided vehicle (AGV (<NUM>)) including a robot arm (<NUM>) for positioning the cassette in the wet bath and removing the cassette from the wet bath, wherein the AGV includes a cassette transfer attachment attached to the robot arm for attaching the AGV to the cassette, and wherein the cassette transfer attachment includes a cassette clip for attaching to the cassette transfer attachment to the cassette and a centering rod for positioning the cassette within the wet bath when the AGV positions the cassette within the wet bath.