QUARTZ BOAT METHOD AND APPARATUS FOR THIN FILM THERMAL TREATMENT
A method of supporting a plurality of planar substrates in a tube shaped furnace for conducting a thermal treatment process is disclosed. The method uses a boat fixture having a base frame including two length portions and a first width portion, a second width portion, and one or more middle members connected between the two length portions. Additionally, the method includes mounting a removable first grooved rod respectively on the first width portion, the second width portion, and each of the one or more middle members, each first grooved rod having a first plurality of grooves characterized by a first spatial configuration. The method further includes inserting one or two substrates of a plurality of planar substrates into each groove in the boat fixture separated by a distance.
1 . An apparatus for holding substrates for thermal treatment comprising:
a frame fixture having a substantially rectangular prism shape, the frame fixture including a base frame, a top frame, side connection bars coupling the base frame and the top frame, the base frame having two width members and middle joint members connected between the two length members;
a first grooved rod removably mounted on each of the two width members and each of the middle joint members, each first grooved rod including a first plurality of grooves for supporting planar substrates;
a first grooved bar removably mounted on each of two width members of the top frame, each first grooved bar including a second plurality of grooves aligned with the first plurality of grooves for guiding the plurality of planar substrates into the apparatus; and
a rack structure configured to be a mechanical support of the frame fixture in a loading position inside a furnace for subjecting the plurality of planar substrates in the first configuration to one or more reactive thermal treatment processes.
2 . The apparatus of claim 1 wherein the frame fixture and the first grooved rod and the first grooved bar comprise quartz.
3 . The apparatus of claim 1 wherein each of the plurality of planar substrates comprises glass having at least one surface overlaid by a photovoltaic precursor layer which includes at least copper, indium, and gallium species.
4 . The apparatus of claim 1 wherein each of the plurality of planar substrates comprises a piece of soda lime glass having a form factor selected at least from a 65 cm×165 cm rectangle, a 20 cm×50 cm rectangle, a 20 cm×20 cm square.
5 . The apparatus of claim 1 wherein the first configuration comprises an arrangement of the plurality of planar substrates in a substantially vertical orientation and parallel to a neighboring planar substrate at a distance equal to or greater than a predetermined value associated with at least the furnace and the one or more thermal treatment processes.
6 . The apparatus of claim 5 wherein the predetermined value comprises a minimum spacing for maintaining a sufficient convection flow so that a temperature difference across each planar substrate is smaller than 15 degrees Celsius at least during a dwell stage of the thermal treatment processes.
7 . The apparatus of claim 6 further comprising a second grooved rod for replacing the first grooved rod to mount on each of the two width members and each of the one or more middle joint members, each second grooved rod including a second plurality of grooves respectively configured to support a plurality of planar substrates in a second configuration, each groove supporting at least one planar substrate.
8 . The apparatus of claim 7 wherein the second configuration comprises an arrangement of the plurality of planar substrates substantially parallel to each other with a front/back surface of one planar substrate facing another front/back surface of a neighboring planar substrate at a first/second distance away, the first distance being equal to or greater than the predetermined value, the second distance being substantially smaller than the first distance.
9 . The apparatus of claim 8 wherein the front surface of each planar substrate comprises a precursor layer being subjected to the one or more thermal treatment processes.
10 . The apparatus of claim 8 wherein the second distance is substantially zero and each groove is configured to support two planar substrates in back-to-back configuration.
11 . The apparatus of claim 1 wherein the furnace is made of quartz material for enclosing a volume configured to form a gaseous environment comprising at least selenium species or sulfur species during the one or more thermal treatment processes.