Method for using a sample holder for rotary coating systems for rotary coating

Abstract

Method for using a sample holder for rotary coating systems for a rotary coating process, wherein the sample holder comprises at least one disk with a recess for vacuum suction and a means for securing the sample holder, the disk having a thickness of at least 0.3 cm and not more than is permitted by a rotary coating system, and made of a material with a thermal conductivity λ in the range of 15 W / (m·K) ≤ λ ≤ 5300 W / (m·K) and a heat storage capacity s ≥ 2000 kJ / (m²·K). 3 ·K) is manufactured, given by the steps: a. Providing the sample holder, b. Provision of the rotary coating system; c. Providing a means of temperature control; d. Tempering the sample holder outside the rotary coating system using the tempering agent and e. within 5 - 60 seconds, positioning the sample holder in the rotary coating system as well as positioning a workpiece and f. within a further 5 – 60 seconds, the rotary coating process begins.

Description

[0001] The invention relates to a method for using a sample holder for rotary coating systems for a rotary coating, such as those known in chemical process engineering.

[0002] It is generally known that reactions and processes in chemistry, and especially in physical chemistry, can be temperature-dependent. In physical chemistry, this primarily concerns the kinetics of reactions, i.e., the rate and time course of the reaction, transport processes such as diffusion, evaporation, solidification, and, in particular, crystallization, among others. The manipulation of reactions and processes with regard to temperature-dependent processes, as exemplified above, is therefore a subject of study in chemical and electrochemical process engineering. Temperature can be adjusted and controlled in various ways, both by increasing (heating) and reducing (cooling). Examples include direct contact with a heating plate or heat sink (conduction), contact with a heating medium or cooling fluid, as is common in heat exchangers, or, for example,Simply via thermal radiation. Some reactions or processes also require a specific atmosphere in which to take place, or can be influenced by one. An example is an inert atmosphere for reactions or processes involving substances that are sensitive to oxygen and / or water, or reactions that are accelerated by an increased partial pressure of oxygen. Furthermore, atmospheric pressure (overpressure and underpressure) also influences some reactions. This applies to processes or reactions that are carried out at a temperature different from ambient temperature and under a defined gas atmosphere in a flow-through environment.

[0003] One example where all these circumstances of reactions and processes must be considered is rotational coating for the production of thin films, such as those used in the manufacture of perovskite solar cells, which have been the subject of increased research since 2012. In rotational coating, liquids are deposited onto a workpiece, usually a flat disk such as a (glass or silicon) wafer. These liquids can be solution mixtures that react after coating, with the excess solution evaporating, or solutions whose solid components solidify and / or crystallize on the wafer / substrate through solvent evaporation. The kinetics of solvent evaporation, particularly for layers intended for crystallization, influence the quality and type of crystallization. Evaporation is especially temperature-dependent and also depends on other factors, such as...The process depends on the flow rate of a gas and the pressure. During deposition, the workpiece is rotated, for which it is fixed to a rotary table by means of vacuum suction. The rotary tables used for vacuum suction of workpieces (such as the aforementioned glass or silicon substrates) are referred to in this application as sample holders and are also commonly called "chucks." Rotational coating processes achieve speeds of several thousand revolutions per minute (in exceptional cases) and otherwise up to 10,000 rpm, so that a defined layer thickness can be created by the runoff of excess solution from the workpiece onto the workpiece.

[0004] JP H07 221 062 A discloses a sample holder for rotary coating systems, comprising a disc with a recess for vacuum suction and a means for securing the sample holder. The disc is approximately 0.64 cm thick and made of stainless steel with a titanium coating. A sample holder of the same design is also described in US 2019 / 0252233 A1.

[0005] A method for temperature control of a sample holder for rotary coating systems is disclosed in JP 2020 188 251 A. The sample holder is arranged within the rotary coating system and temperature-controlled by a temperature control device, which includes liquid cooling or heating. The temperature control device is pressed onto the sample holder within the system to equalize the temperature.

[0006] In JP 2005-79 328 A, the sample holder with the applied substrate undergoes pretreatment in various processing units, including a cooling unit and a heating unit. The sample holder and substrate are automatically transferred between the processing units. Task

[0007] The object of the invention is to provide a sample holder for rotary coating systems that enables more precise and ideal temperature control compared to the prior art. The sample holder also allows for a simplified rotary coating system that is therefore easy to reproduce and manufacture.

[0008] The problem is solved by the subject matter of claim 1.

[0009] The sample holder for rotary coating systems comprises at least one disk with a recess for vacuum suction and a means for securing the sample holder. The disk is crucial for the functionality of the invention and is described below. The sample holder and the securing means can be formed integrally. The recess for vacuum suction must always be arranged rotationally symmetrically in the center of the disk, where the securing means is also located. This means that the securing means must be hollow, for example, in the form of a tube or pin with a central bore. Additionally, a recess can be provided at the outlet of the recess in the disk. The securing means serves to clamp the sample into a rotary coating system and interacts with it, for example, by means of a positive fit.

[0010] A disk within the meaning of the invention is a geometric body in the form of a flat circular cylinder and is bounded by two parallel side surfaces and an edge.

[0011] The disk of the sample holder is made of a material with high thermal conductivity, i.e. a thermal conductivity λ in the range of 15 W / (m·K) ≤ λ ≤ 5300 W / (m·K) (stainless steel to graphene).

[0012] The material of the sample holder disc also exhibits a heat storage capacity (also referred to as specific volumetric heat capacity) s ≥ 2000 kJ / (m²). 3 ·K). The heat storage capacity is limited only by the materials suitable for the specimen holder, which typically have a maximum heat storage capacity of ~ 4000 kJ / (m²). 3 exhibit ·K).

[0013] The disc is made, for example, from one of the materials in the group comprising aluminum, iron, nickel, gold, silver, titanium, platinum, their alloys, and steel. Optimization should also be carried out with regard to the material's resistance during the manufacturing process. Cost considerations can also be a selection criterion.

[0014] The disc has a thickness of at least 0.3 cm. The thickness is limited by the maximum thickness achievable by a rotary coating system without impairing the system's function after the sample holder is installed. Maximizing the thickness under the aforementioned constraint is advantageous from the perspective of the invention's functionality. Typically, the thickness will not exceed 1 cm under these conditions.

[0015] The disc is further characterized by the fact that its sides and edge are flat and smooth (average roughness Ra ≤ 1, finely finished) and profile-free, i.e. without indentations, scratches, etchings or other introduced / impressed structure.

[0016] The material used according to the invention, in combination with the thickness of the disc according to the invention, provides the advantage of the invention, which lies in the thermal inertia of the heat exchange, resulting from the thickness and material of the sample holder. The thermal inertia of the sample holder arises from its high volumetric heat capacity and the low, design-related (radiative and conductive) heat losses. The heat absorption or dissipation of the sample holder is limited to radiative effects and very weak conductive heat exchange effects with the surroundings. The thermal inertia of the sample holder is particularly advantageous when the workpiece to be coated is exchanged and the process chamber is flooded with ambient air and thus heated accordingly.Due to its inertia, the chuck according to the invention maintains a previously assumed temperature for a longer period, which allows for re-tempering in a shorter time and maintains the desired temperature for a longer period and with a slower rate of change.

[0017] The sample holder is used according to the following method according to the invention to achieve the advantage of simplified handling. Before use, the sample holder is tempered in a rotary coating system and promptly inserted into the system, i.e., within 5–60 seconds, and fitted with a workpiece (e.g., a glass or silicon substrate). Coating then begins within a further 5–60 seconds. Tempering of the sample holder is carried out using a temperature control device such as an oven, a hot plate, a refrigerator, a cryostat, or an ice bath. The tempering time depends on the volume of the sample holder, the material from which it is made, and the target temperature T. pand may need to be determined experimentally, which can be achieved using common methods known to those skilled in the art. Typically, a duration of 5 seconds to 15 minutes is expected until the desired temperature of the component is reached. In the process, the sample holder is first placed and heated in the temperature control device, then removed from it and inserted into a rotary coating system (time frame see above). A workpiece is then placed on the sample holder and secured by applying a vacuum, after which the coating is applied. Advantageously, according to the invention, the temperature control takes place outside the rotary coating system, thus simplifying the handling of the sample holder and the system itself.

[0018] The achievable temperature ranges of the component (invention) presented here depend on the material properties of the selected material of the component (invention) and the temperature tolerances of the components in contact with the component. In principle, temperature ranges between -20°C ≤ T are achievable with standard laboratory equipment (laboratory refrigerator or freezer, hot plate). p to reach ≤ 120°C. Example of implementation

[0019] The invention is described in more detail with reference to an exemplary embodiment and a figure.

[0020] The figure shows: Fig. 1: Schematic cross-sectional representation of a generic sample holder according to the state of the art.

[0021] In the Fig.Figure 1 schematically shows an embodiment of a sample holder 1. The sample holder 1 comprises a disk 2, 0.7 cm thick, made of aluminum and with a diameter of 8 cm. The disk 2 is equipped with a pin 3 with a locking groove (as a means of securing it) for positive-locking and gas-tight insertion into a rotary coating system. The disk 2 and the pin 3 are provided with a through bore 4 (as a recess) extending through both parts. The bore 4 can also be provided with recesses at its exit from the disk, as shown in the figure with two examples 4a and 4b. A workpiece is positioned on the disk at the exit of the bore 4 or the recesses 4a and 4b, so that these are covered, and then drawn in by vacuum and thus held in place.

[0022] In the inventive method, the sample holder 1 is heated to 100 °C for 2 minutes on a heating plate and, within 30 seconds of being removed from the heating plate, is placed in a rotary coating system. Within a further 30 seconds, a workpiece is placed in the system and the coating process begins. An example of temperature reduction would be cooling the component to -5 °C for 10 minutes in a laboratory freezer, following the same sequence of steps as previously described.

[0023] This demonstrates the advantages of the invention, namely its simplified handling and overall simplified system compared to the prior art. No additional temperature control device is required.

Claims

[1] Method for using a sample holder for rotary coating systems for a rotary coating, wherein the sample holder comprises at least one disk with a recess for vacuum suction and a means for securing the sample holder, the disk having a thickness of at least 0.3 cm and not more than is permitted by a rotary coating system and made of a material having a thermal conductivity λ in the range of 15 W / (m·K) ≤ λ ≤ 5300 W / (m·K) and a heat storage capacity s ≥ 2000 kJ / (m 3 ·K) is manufactured, given by the steps: a. Providing the sample holder, b. Provision of the rotary coating system; c. Providing a means of temperature control; d. Tempering the sample holder outside the rotary coating system using the tempering agent and e. within 5 - 60 seconds, positioning the sample holder in the rotary coating system as well as positioning a workpiece and f. within a further 5 – 60 seconds, the rotary coating process begins.

Images