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JP-7855528-B2 - A method for controlling the evaporation rate of a source material, a detector for measuring electromagnetic radiation reflected from the source surface, and a system for thermal evaporation by electromagnetic radiation.

JP7855528B2JP 7855528 B2JP7855528 B2JP 7855528B2JP-7855528-B2

Inventors

  • ブラウン，ウルフギャング

Assignees

  • マツクス－プランク－ゲゼルシヤフト ツール フエルデルング デル ヴイツセンシヤフテン エー フアウ

Dates

Publication Date
20260508
Application Date
20200630

Claims (20)

  1. A method for controlling the evaporation rate of a source material (20) in a system (10) for thermal evaporation by electromagnetic radiation (120), The system (10) includes an electromagnetic radiation source (110) that provides electromagnetic radiation (120), a vacuum chamber (12) that houses a reaction atmosphere (16), and main detectors (40, 100) that measure the electromagnetic radiation (120). The source material (20) and the target material (18) to be coated are arranged inside the vacuum chamber (12). The electromagnetic radiation source (110) is configured such that its electromagnetic radiation (120) is incident at a predetermined angle on the source surface (22) of the source material (20) for thermal evaporation and/or sublimation of the source material (20) below the plasma threshold. The main detectors (40, 100) for measuring electromagnetic radiation (120) are configured such that the electromagnetic radiation (120) reflected from the source surface (22) reaches the main detectors (40, 100), and further, The aforementioned source material (20) is provided by the source element (24), The source surface (22) is positioned on the source element (24) in a manner that allows access to the electromagnetic radiation (120), the source element (24) is positioned within a holding structure (28) and is movable by the holding structure (28) perpendicular to the source surface (22), The aforementioned method, a) The step of providing the electromagnetic radiation (120) by the electromagnetic radiation source (110), b) A step of measuring the electromagnetic radiation (120) reflected on the source surface (22) by the main detector (40, 100), c) A step of analyzing the measured data obtained in step b), d) Adjusting the evaporation rate based on the results of the analysis in step c) by moving the source element (24) in relation to the electromagnetic radiation (120), and/or adjusting the power of the electromagnetic radiation (120), and/or adjusting the size and/or shape of the cross-section of the electromagnetic radiation (120), A method in which, in step b), the main detector (40, 100) having two or more sensor elements (50) is used, the two or more sensor elements (50) are adjacent to each other and thermally discoupled.
  2. The method according to claim 1, wherein in step d), the source element (24) is moving perpendicular and/or parallel to the source surface (22).
  3. The method according to claim 1 or 2, wherein the source element (24) is provided as a self-supporting structure having a source material (20) including the source surface (22) positioned at the upper end of the source element (24) .
  4. The aforementioned source element (24) is provided as a rod (30), The rod (30) is provided with a circular or at least fundamentally circular rod (30) cross-section. The electromagnetic radiation (120) is provided with an elliptical beam cross-section. The method according to claim 3, wherein the cross section of the rod (30) and the cross section of the beam are selected in a mutually compatible state.
  5. The source element (24) has a crucible (34) containing the source material (20), The method according to claim 1 or 2, wherein the crucible (34) is transparent or at least partially transparent with respect to the electromagnetic radiation (120) when the source surface (22) is positioned within the crucible (34).
  6. The method according to any one of claims 1 to 5, wherein the electromagnetic radiation (120) light used is laser light having a wavelength of 100 nm to 1400 nm.
  7. The method according to any one of claims 1 to 6, wherein in step b), a first further detector (40, 102) is used to measure electromagnetic radiation (120) reflected on a side surface (26) of the source element (24) that is different from the source surface (22), so that the data measured by the first further detector (40, 102) is used in steps c) and d).
  8. The method according to claim 7, wherein the side surface (26) of the source element (24) is provided in a flat state.
  9. The method according to claim 8, wherein the flat side surface (26) is oriented perpendicular to a plane covered by the direction of the electromagnetic radiation (120) incident on and reflected from the source surface (22).
  10. The method according to any one of claims 1 to 9, wherein in step b), a second additional detector (40, 104) is used to measure electromagnetic radiation (120) that has escaped the source surface (22) of the source element (24), and the data measured by the second additional detector (40, 104) is used in steps c) and d).
  11. A detector (40) for measuring electromagnetic radiation (120) reflected from a source surface (22), having a sensor element (50) having an absorption body (52), The absorbing body (52) has an absorbing surface (60) that absorbs the electromagnetic radiation (120) at least partially, The sensor element (50) further includes a thermal sensing element (70) that measures the temperature of the absorption body (52) in order to detect the absolute temperature and/or temperature change generated within the absorption body (52) due to the absorbed electromagnetic radiation (120). The absorbent body (52) has a cooling system (80) for active cooling of the absorbent body (52), The cooling system (80) has at least one cooling duct (82) within the absorption body (52) for the flow of coolant (84) through the absorption body (52), The heat sensing element (70) includes a flow sensor (72) for measuring the flow of the coolant (84) through the cooling duct (82) in the absorption body (52), and a temperature sensor (74) for measuring the absolute temperature of the coolant (84) and/or the temperature change of the coolant (84) induced by the flow through the cooling duct (82) in the absorption body (52). The detector has two or more of the sensor elements (50), A detector (40) in which two or more of the aforementioned sensor elements (50) are adjacent to each other and thermally discoupled.
  12. The detector (40) according to claim 11, wherein one or more detectors can be used in the method of any one of claims 1 to 10 as a main detector (40, 100) and/or as a first further detector (40, 102) and/or as a second further detector (40, 104).
  13. The detector (40) according to claim 11 or 12, wherein the absorbing surface (60) absorbs light having a wavelength of 100 nm to 1400 nm.
  14. The heat sensing element (70) has a temperature sensor (74 ) positioned within the bore (54) in the absorption body (52), The detector (40) according to any one of claims 11 to 13, wherein the bore (54) is terminated within the absorption body (52).
  15. The detector (40) according to any one of claims 11 to 14, wherein the absorption body (52) is made of metal .
  16. The absorbent body (52) has a hollow absorbent volume (56) sealed inside at one end, and as a result, the inner side wall (58) of the absorbent volume (56) forms the absorbent surface (60). The detector (40) according to any one of claims 11 to 15, wherein the absorption volume (56) has an absorption orifice (62), thereby allowing the absorption orifice (62) to be aligned with the assumed and/or determined incident direction (122) of the electromagnetic radiation (120) to be measured.
  17. The absorption surface (60) is partially formed into a conical shape within the absorption volume (56). The detector (40) according to claim 16, wherein the cone of the conically shaped absorption surface (60) faces the absorption orifice (62).
  18. The detector (40) according to claim 16 or 17, wherein the portion of the absorption volume (56) forming the edge (64) of the absorption orifice (62) is inclined inward in relation to the absorption volume (56).
  19. The detector has an aperture (90) having an aperture opening (92), The detector (40) according to any one of claims 11 to 18, wherein the aperture (90) is positioned upstream of the sensor element (50) in relation to the assumed and/or determined incident direction (122) of the electromagnetic radiation (120) to be measured.
  20. The detector (40) according to claim 19, wherein the size of the aperture opening (92) is adapted to the absorbing body (52) such that electromagnetic radiation (120) arriving through the aperture opening (92) is incident on the absorbing surface (60) of the absorbing body (52).

Description

This invention relates to a method for controlling the evaporation rate of a source material in a system for thermal evaporation by electromagnetic radiation, wherein the system comprises an electromagnetic radiation source that provides electromagnetic radiation, a vacuum chamber containing a reaction atmosphere, and a main detector for measuring electromagnetic radiation, the source material and the target material to be coated are arranged in the vacuum chamber, the electromagnetic radiation source is configured such that its electromagnetic radiation is incident on the source surface of the source material at a predetermined angle, preferably 45°, for thermal evaporation and/or sublimation of the source material below the plasma threshold, the main detector for measuring electromagnetic radiation is configured such that the electromagnetic radiation reflected from the source surface reaches the main detector, and furthermore, the source material is provided by a source element, the source surface is arranged in a state accessible to electromagnetic radiation on the source element, thereby the source element is arranged within a holding structure and is movable by the holding structure. Furthermore, the present invention relates to a detector for measuring electromagnetic radiation reflected from a source surface, comprising a sensor element having an absorbing body, wherein the absorbing body has an absorbing surface that at least partially absorbs electromagnetic radiation, and the sensor element further comprises a thermal sensing element that measures the temperature of the absorbing body to detect the absolute temperature and/or temperature change generated within the absorbing body by the absorbed electromagnetic radiation. In addition, the present invention relates to a system for thermal evaporation by electromagnetic radiation, comprising an electromagnetic radiation source that provides electromagnetic radiation, a vacuum chamber that contains a reaction atmosphere, and a main detector that measures the electromagnetic radiation, wherein the source material and the target material to be coated are arranged within the vacuum chamber, the electromagnetic radiation source is configured such that its electromagnetic radiation is incident on the surface of the source material at a predetermined angle, preferably 45°, for thermal evaporation and/or sublimation of the source material below the plasma threshold, and the main detector that measures the electromagnetic radiation is configured such that the electromagnetic radiation reflected from the source surface reaches the main detector. The use of electromagnetic radiation, particularly lasers with wavelengths in the visible, infrared, or ultraviolet ranges, for the evaporation of source materials is commonly known. Such laser evaporation systems allow for the deposition of thin films of material at low pressure by heating the center of a block of source material from the front with a continuous-wave laser. For example, silicon achieves the desired flow of evaporated material, thereby melting at the temperature required to form a molten pool inside the solid portion of the same source material. Thus, solid Si forms a crucible for liquid Si, allowing for very large heating and cooling rates due to the absence of thermal expansion mismatch between the source material and the crucible. At the same time, any contamination of the source material by different crucible materials is avoided. Alternatively, crucibles made of materials different from the material to be evaporated are also used. However, as the source material is consumed by incident electromagnetic radiation, the source surface changes shape. For example, the molten pool takes on a recessed form and/or sublimation spots are increasingly carved deeper into the source material. Therefore, since the shape of the source surface directly affects the evaporation rate and the flow distribution of the evaporated material, the evaporation rate and flow distribution of the evaporated source material are inherently unstable. A known method for overcoming this problem involves moving a spot of electromagnetic radiation across the source material to obtain a relatively uniform distribution of energy storage and, consequently, evaporated source material. Furthermore, since the support points for the source material are almost always located at its outer edge, close to the evaporation surface, evaporation or sublimation from the entire surface of the source is impractical. In addition, because the evaporation surface still does not strictly maintain a constant shape and/or orientation, at least in time, the motion of the source itself introduces fluctuations. This is a system according to the present invention.This is a first possible embodiment of the detector according to the present invention.It is an absorbent body with an absorption volume.This is one embodiment of a detector according to the present i