How Many Hot And Cold Plates Are There in The Homogenizer/developer?

What is track?

The Track System in the lithography process is used for the coating, baking, development and other steps of the photoresist in the lithography process. It can be used with the exposure machine to complete the whole process from gluing to developing. If the track, the exposure machine is separated, there is no direct physical connection integrated together, it is called "offline". If the exposure machine and track are connected together, it is called "inline". I wrote yesterday, "KrF lithography machine has several hot plate and cold plate", did not specify clearly, causing some misunderstandings, in fact, I am referring to the integrated KrF lithography machine "inline" requires the number of hot plate and cold plate.


The role of hot plate and cold plate
Hot plate: After the photoresist is coated, it is soft baked with a hot plate to remove solvents and improve its viscosity; After exposure, the hot plate is used to carry out the PEB process to further expel the residual solvent, stabilize the structure of the photoresist, and reduce the deformation and blurring after exposure. After development, a hot plate is used to harden the film to enhance the corrosion resistance of the photoresist.

Cold plate: After each hot drying step, the natural cooling time is too long, in order to improve efficiency, you need to use cold plate fast cooling photoresist. This helps to cure photoresist quickly, reducing thermal stress and thermal deformation.

Number configuration of hot plate and cold plate in track
According to the characteristics of hot plate and cold plate, as well as the requirements of each process, the track machine is generally multi-chamber in the wafer fab. In the multi-chamber track machine, the number of hot plates is relatively more, so the number of hot plates is greater than the number of cold plates, and can be configured according to the ratio of 4:1 or 3:1. A 1:1 ratio has also been seen in track machines with a small number of chambers, or in some dry film developers. Of course, the core of the configuration is not to let the wafer wait for the next process for a long time, and rational use of the machine. For example, there are 4 chambers with a certain type of track machine, and 10 positions are reserved for hot plate and cold plate, so there can be 8 hot plates and 2 cold plates.
Temperature of hot plate and cold plate
Generally, the upper limit temperature of the hot plate is within 200 ° C, and the cold plate should be connected to the PCW cycle to cool down. Because the temperature is too high will lead to the photoresist deformation, reflux, there is no need to set a high temperature upper limit.