A method for calibrating phosphorus beam in molecular beam epitaxy system

Abstract

The present invention provides a method for calibrating a phosphorus beam in a molecular beam epitaxy system, and relates to the technical field of semiconductor manufacturing. The method comprises: growing InGaAs in a first molecular beam epitaxy system in which the phosphorus beam has been calibrated; y0 P 1‑y0 Epitaxial layer; InGaAs is grown in the second molecular beam epitaxy system to be calibrated with phosphorus beam y P 1‑y Epitaxial layer, by adjusting the value of phosphorus beam current, the As component y actually measured is equal to y0, and the phosphorus beam current corresponding to y equal to y0 is used as the calibrated phosphorus beam current of the second molecular beam epitaxy system. The present application determines the relative size relationship between the arsenic beam current and the phosphorus beam current actually required in different systems by growing InGaAsP materials with fixed components in different molecular beam epitaxy systems, and then uses the arsenic beam current calibration data and the relative size relationship to realize the phosphorus beam current calibration of the new system. This method can significantly save time and material costs.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor manufacturing, and in particular to a calibration method for a phosphorus beam in a molecular beam epitaxy system. Background Art

[0002] In the large-scale growth of molecular beam epitaxy (MBE), precise control of the molecular beam is crucial. For the epitaxial growth of III-V compounds, the beam rate of the III-V elements determines the growth rate of the epitaxial material, and the beam of the V-V elements is usually oversupplied to obtain high-quality crystalline materials. For example, in the epitaxial growth of GaAs, while oversupplying arsenic, unnecessary waste of arsenic source is avoided. The arsenic beam is usually supplied at 2.5 to 3.5 times the minimum required beam current. The minimum required beam current of the arsenic beam is usually determined by gradually reducing the arsenic beam supply during the molecular beam epitaxy of the GaAs sample at a preset fixed temperature and preset Ga beam conditions, and observing the arsenic beam current corresponding to the transformation of the sample surface reconstructed RHEED pattern from As-rich (2×4) stripes to Ga-rich (4×2) stripes.

[0003] For the growth of phosphide on InP substrate, phosphorus beam also needs to be oversupplied, but the minimum required beam of phosphorus beam cannot be determined by observing the transition of RHEED pattern like arsenic beam. In practical applications, InP epitaxial layer can be epitaxially grown on InP substrate to obtain corresponding epitaxial wafer by adopting different phosphorus beams respectively, and the quality of epitaxial wafer obtained under different beams can be tested and analyzed respectively to determine suitable phosphorus beam. Since the total amount of phosphorus that can be filled in the phosphorus source furnace of conventional molecular beam epitaxy system is much less than arsenic, in order to save phosphorus source, it is necessary to determine phosphorus beam as accurately as possible, and it is not possible to oversupply, which just needs to carry out a large amount of tentative tests, consuming material cost and time cost. Therefore, it is necessary to propose a calibration method of phosphorus beam in molecular beam epitaxy system. Summary of the invention

[0004] The object of the present invention is to provide a method for calibrating a phosphorus beam in a molecular beam epitaxy system to solve the problem of calibrating the phosphorus beam, in view of the above-mentioned deficiencies in the prior art.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] The present invention provides a method for calibrating a phosphorus beam in a molecular beam epitaxy system, the method comprising:

[0007] In a first molecular beam epitaxy system where the phosphorus beam current has been calibrated, an InP substrate having a preset thickness is grown at a preset growth temperature on a first InP substrate. x0 Ga 1-x0 Asy0 P 1-y0 The epitaxial layer, where x0 represents the component of In in group III elements, y0 represents the component of As in group V elements, and 0.53 < x0 < 1, 0 < y0 < 1. During the growth of In x0 Ga 1-x0 As y0 P 1-y0 epitaxial layer, the phosphorus beam current is the preset first beam current, the arsenic beam current is the preset second beam current. By selecting the value of x0, the In x0 Ga 1- x0 As y0 P 1-y0 epitaxial layer is lattice-matched with the InP substrate. In the first molecular beam epitaxy system, when the surface reconstruction RHEED pattern of the preset specification GaAs material during molecular beam epitaxy changes from the As-rich (2×4) stripe to the Ga-rich (4×2) stripe at the preset fixed temperature and the preset Ga beam current, the corresponding arsenic beam current is the third beam current;

[0008] In the second molecular beam epitaxy system for calibrating the phosphorus beam current, on the second InP substrate with the same specification as the first InP substrate, using the preset growth temperature, grow an In x0 Ga 1-x0 As y P 1-y epitaxial layer. By adjusting different values of the phosphorus beam current, respectively carry out the growth of the In x0 Ga 1-x0 As y P 1-y epitaxial layer. Finally, make the actually measured As component y equal to y0, and take the value of the phosphorus beam current corresponding to the As component y equal to y0 as the calibrated phosphorus beam current of the second molecular beam epitaxy system. In the second molecular beam epitaxy system, when the surface reconstruction RHEED pattern of the preset specification GaAs material during molecular beam epitaxy changes from the As-rich (2×4) stripe to the Ga-rich (4×2) stripe at the preset fixed temperature and the preset Ga beam current, the corresponding arsenic beam current is the fourth beam current. During the growth of the In x0 Ga 1-x0 As y P 1-y epitaxial layer, the arsenic beam current is the fifth beam current, and the fifth beam current = (the fourth beam current / the third beam current) × the second beam current.

[0009] Optionally, the value range of the second beam current is one-fifth to 2 times of the third beam current.

[0010] Optionally, the value of the second beam current is equal to the third beam current.

[0011] Optionally, the value range of the first beam current is 2 to 3 times the minimum phosphorus beam current required for growing an InP epitaxial layer on an InP substrate in the first molecular beam epitaxy system. The growth rate of In during the growth of the InP epitaxial layer is the same as the growth rate of In during the growth of the In x0 Ga 1- x0 As y0 P 1-y0 epitaxial layer.

[0012] Optionally, the value range of the preset thickness is 200 nm to 600 nm.

[0013] Optionally, the value range of the preset thickness is 300 nm to 400 nm.

[0014] The beneficial effects of the present invention include:

[0015] The method for calibrating the phosphorus beam current in the molecular beam epitaxy system provided by the present invention includes: in the first molecular beam epitaxy system where the phosphorus beam current has been calibrated, on the first InP substrate, using a preset growth temperature, growing an In x0 Ga 1-x0 As y0 P 1-y0 epitaxial layer with a preset thickness, x0 represents the component of In in the group III elements, y0 represents the component of As in the group V elements, and 0.53 < x0 < 1, 0 < y0 < 1. During the growth of the In x0 Ga 1-x0 As y0 P 1-y0 epitaxial layer, the phosphorus beam current is the preset first beam current, and the arsenic beam current is the preset second beam current. By selecting the value of x0, the In x0 Ga 1-x0 As y0 P 1-y0 epitaxial layer is lattice-matched with the InP substrate. In the first molecular beam epitaxy system, when the surface reconstruction RHEED pattern of the preset specification GaAs material changes from the As-rich (2×4) stripes to the Ga-rich (4×2) stripes during the molecular beam epitaxy process at the preset fixed temperature and the preset Ga beam current, the corresponding arsenic beam current is the third beam current; in the second molecular beam epitaxy system to be calibrated for the phosphorus beam current, on the second InP substrate with the same specification as the first InP substrate, using the preset growth temperature, growing an In x0 Ga 1-x0 As y P 1-y epitaxial layer, by adjusting different values of the phosphorus beam current, respectively performing In x0 Ga 1-x0 As y P 1-yThe growth of the epitaxial layer finally makes the As component y actually measured equal to y0, and the value of the phosphorus beam current corresponding to the As component y equal to y0 is used as the calibrated phosphorus beam current of the second molecular beam epitaxy system. In the second molecular beam epitaxy system, the GaAs material with preset specifications is subjected to the molecular beam epitaxy process at a preset fixed temperature and a preset Ga beam. When the surface reconstructed RHEED pattern changes from As-rich (2×4) stripes to Ga-rich (4×2) stripes, the corresponding arsenic beam current is the fourth beam current. When growing In x0 Ga 1-x0 As y P 1-y During the epitaxial layer growth process, the arsenic beam is the fifth beam, and the fifth beam = (fourth beam / third beam) × second beam. The present application determines the relative size relationship between the arsenic beam and the phosphorus beam actually required in the epitaxial growth process in different systems by growing InGaAsP materials with fixed In and As components in different molecular beam epitaxy systems, and then uses the calibration data and relative size relationship of the arsenic beam to calibrate the phosphorus beam of the new molecular beam epitaxy system. This method is efficient and reliable, and can significantly save time and material costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A schematic flow chart of a method for calibrating a phosphorus beam in a molecular beam epitaxy system provided by an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] For the epitaxial growth of group III-V compounds, the beam flux rate of group III elements determines the growth rate of the epitaxial material, and the beam flux of group V elements is usually supplied in excess to obtain high-quality crystal materials. For example, in the epitaxial growth of GaAs, while supplying arsenic in excess, unnecessary waste of the arsenic source is avoided, and the arsenic beam flux is usually supplied in an amount 2.5 to 3.5 times the minimum required beam flux. The minimum required beam flux of the arsenic beam is usually determined by observing the corresponding arsenic beam flux when the RHEED pattern of the sample surface reconstructs from the As-rich (2×4) stripes to the Ga-rich (4×2) stripes during molecular beam epitaxy of the GaAs sample under a preset fixed temperature and a preset Ga beam flux condition. For the growth of phosphides on an InP substrate, the phosphorus beam flux also needs to be supplied in excess. However, the minimum required beam flux of the phosphorus beam cannot be determined by observing the transition of the RHEED pattern like the arsenic beam flux. In practical applications, by using different phosphorus beam fluxes respectively, an InP epitaxial layer is grown on an InP substrate to obtain corresponding epitaxial wafers, and the quality of the epitaxial wafers obtained under different beam fluxes is respectively tested and analyzed to determine the appropriate phosphorus beam flux. Since the amount of phosphorus that can be loaded in the phosphorus source furnace of a conventional molecular beam epitaxy system is much less than that of arsenic, in order to save the phosphorus source, it is necessary to determine the phosphorus beam flux as accurately as possible without excessive over-supply, which requires a large number of trial experiments, consuming material costs and time costs. Therefore, a method for calibrating the phosphorus beam flux in a molecular beam epitaxy system needs to be proposed.

[0020] Figure 1 The flow chart showing the method for calibrating the phosphorus beam flux in the molecular beam epitaxy system provided by the embodiment of the present invention is shown. As Figure 1 shown, the method for calibrating the phosphorus beam flux in the molecular beam epitaxy system provided by the present invention includes:

[0021] Step 11: In the first molecular beam epitaxy system where the phosphorus beam flux has been calibrated, on the first InP substrate, grow In x0 Ga 1-x0 As y0 P 1-y0 epitaxial layer with a preset thickness at a preset growth temperature.

[0022] Wherein, x0 represents the component of In in group III elements, y0 represents the component of As in group V elements, and 0.53 < x0 < 1, 0 < y0 < 1. During the growth of the In x0 Ga 1-x0 As y0 P 1-y0 epitaxial layer, the phosphorus beam flux is the preset first beam flux, and the arsenic beam flux is the preset second beam flux. By selecting the value of x0, the In x0 Ga 1-x0 As y0 P1-y0 The epitaxial layer is lattice matched to the InP substrate. In the first molecular beam epitaxy system, when the surface reconstructed RHEED pattern of GaAs material with preset specifications changes from As-rich (2×4) stripes to Ga-rich (4×2) stripes at a preset fixed temperature and a preset Ga beam during the molecular beam epitaxy process, the corresponding arsenic beam is the third beam.

[0023] Optionally, the preset thickness ranges from 200 nm to 600 nm. Preferably, the preset thickness ranges from 300 nm to 400 nm.

[0024] It should be understood that the third beam current is determined first, and then the preset second beam current is selected based on the third beam current. Optionally, the value range of the second beam current is from one-fifth of the third beam current to twice the third beam current. Optionally, the value of the second beam current is equal to the third beam current. In addition, the preset first beam current of the phosphorus beam current is selected based on the calibration result of the phosphorus beam current. The value range of the first beam current can be 2 to 3 times the minimum phosphorus beam current required for growing an InP epitaxial layer on an InP substrate in a first molecular beam epitaxy system. The growth rate of In when growing an InP epitaxial layer is the same as that of growing In. x0 Ga 1-x0 As y0 P 1-y0 The growth rate of In in the epitaxial layer is the same.

[0025] In a molecular beam epitaxy system, the surface reconstruction of the sample material is usually observed through the RHEED (reflection high energy electron diffractometer) pattern. In a molecular beam epitaxy system, the beam current is measured by the built-in ion gauge of the molecular beam epitaxy system. Generally speaking, different molecular beam epitaxy systems, due to the influence of the ion gauge installation position, source furnace position and other related factors, the ion gauge measurement values ​​of the same molecular beam current in theory are generally different. Therefore, before using the molecular beam epitaxy system, the beam currents of the five groups of elements need to be calibrated. As mentioned earlier, the calibration of the arsenic beam current is determined by observing the arsenic beam current corresponding to the change of the surface reconstruction RHEED pattern from As-rich (2×4) stripes to Ga-rich (4×2) stripes. After the arsenic beam current is calibrated in the first molecular beam epitaxy system, In can be grown. x0 Ga 1-x0 As y0 P 1-y0For the epitaxial layer, the value of y0 is determined by the relative size of the arsenic (As) beam and the phosphorus (P) beam. At the same growth temperature, if y0 is determined, the relative size of the As beam and the P beam is determined. Conversely, if the relative size of the As beam and the P beam is determined, y0 is determined. Therefore, if the As beam is calibrated, the P beam can be calibrated through the relative size relationship between the As beam and the P beam (determined by y0). In step 11, by determining the phosphorus beam as the preset first beam and the arsenic beam as the preset second beam, the As component y0 can be measured through epitaxial growth. In order to ensure that InGaAs y0 P 1-y0 The high-quality growth of epitaxial layers can be achieved by selecting an appropriate x0 so that In x0 Ga 1- x0 As y0 P 1-y0 The epitaxial layer is lattice matched to the InP substrate.

[0026] In different molecular beam epitaxy systems, the composition x0 of In in the group III elements can be easily calibrated accurately. For example, a thin layer of In can be grown on an InP substrate. x Ga 1-x As or In x Ga 1-x P ternary material (x represents the component of In), and use X-ray diffraction to test the component of In, adjust the temperature of the indium source furnace or the gallium source furnace according to the test results, and finally realize the calibration and determination of the component of In. After the component of In is calibrated to x0, in the subsequent growth process of InGaAsP, the source furnace temperatures of In and Ga are fixed to fix the component of In x0. For the InGaAsP epitaxial layer grown in step 11 or step 12, since the component of In is fixed to x0, an X-ray diffraction test can be used to determine the value of the As component in the epitaxial layer. It should be understood that since the beam value of the present application is only the measurement value of the ion gauge, and the growth temperature also has different degrees of influence on the adhesion coefficient of As and P on the sample surface, therefore, for In to be satisfied x0 Ga 1-x0 As y0 P 1-y0 The As beam current and P beam current for epitaxial layer growth, As beam current / (As beam current + P beam current) is usually not equal to y0 in value.

[0027] As mentioned above, the first molecular beam epitaxy system is a system in which the phosphorus beam has been calibrated. The calibration of the phosphorus beam in the first molecular beam epitaxy system can be a calibration performed according to the present application, or it can be empirical data obtained by using a plurality of different phosphorus beams to grow an indium phosphide epitaxial layer, and performing test and analysis. Therefore, as long as the calibration of one molecular beam epitaxy system is completed, the method of the present application can be used to calibrate other molecular beam epitaxy systems in the future.

[0028] Step 12: In a second molecular beam epitaxy system to be calibrated for phosphorus beam flow, an InP substrate having a preset thickness is grown on a second InP substrate having the same specifications as the first InP substrate at a preset growth temperature. x0 Ga 1-x0 As y P 1-y The epitaxial layer is grown by adjusting the phosphorus beam current to different values. x0 Ga 1-x0 As y P 1-y The growth of the epitaxial layer eventually makes the As composition y actually measured equal to y0, and the value of the phosphorus beam current corresponding to the As composition y equal to y0 is used as the calibrated phosphorus beam current of the second molecular beam epitaxy system.

[0029] In the second molecular beam epitaxy system, the GaAs material with preset specifications is subjected to the molecular beam epitaxy process at a preset fixed temperature and a preset Ga beam current. When the surface reconstructed RHEED pattern changes from As-rich (2×4) stripes to Ga-rich (4×2) stripes, the corresponding arsenic beam current is the fourth beam current. x0 Ga 1-x0 As y P 1-y During the epitaxial layer growth process, the arsenic beam current is the fifth beam current, and the fifth beam current = (fourth beam current / third beam current) × second beam current.

[0030] In the process of adjusting the composition y of the group V element As, since the arsenic beam has been determined as the fifth beam, it is only necessary to adjust the phosphorus beam to achieve the composition y of As equal to y0. For example, an initial value can be given to the phosphorus beam based on experience, and then In can be grown under this condition. x0 Ga 1-x0 As y P 1-y Epitaxial layer, obtain the corresponding epitaxial wafer, and perform test analysis to obtain the corresponding y component. If y>y0, it means that the As component is too high. At this time, it is necessary to increase the phosphorus beam current to reduce the component y, and use the increased phosphorus beam current value as the next In growth x0 Ga 1-x0 As y P 1-yThe phosphorus beam current during the growth of the epitaxial layer; if y < y0, it indicates that the As component is low. At this time, the phosphorus beam current needs to be reduced to increase the component y, and the reduced phosphorus beam current value is used as the next growth In x0 Ga 1-x0 As y P 1-y The phosphorus beam current during the growth of the epitaxial layer. The amplitude of increasing or decreasing the phosphorus beam current can be adjusted with reference to historical experience values, or the phosphorus beam current can be roughly adjusted proportionally according to the values of y and y0 first, and then the subsequent adjusted phosphorus beam current can be determined using an interpolation algorithm based on the measurement results of the component y. Generally speaking, after a few (for example, 2 to 3) tests, the phosphorus beam current corresponding to y = y0 can be determined.

[0031] InP substrates of different specifications (such as substrate size, doping concentration, polishing condition, etc.) will affect the control of the actual growth temperature during the epitaxial growth process. To avoid the influence of different specifications of substrates on the calibration, in step 11 and step 12, it is specified to use InP substrates of the same specification.

[0032] In the second molecular beam epitaxy system, it is specified that the arsenic beam current is the fifth beam current, and the fifth beam current = (the fourth beam current / the third beam current) × the second beam current. Therefore, the arsenic beam current in the second molecular beam epitaxy system and the arsenic beam current in the first molecular beam epitaxy system have the same ratio relative to their respective minimum arsenic beam currents. In other words, when growing the InGaAsP epitaxial layer, the arsenic beam current used in the first molecular beam epitaxy system is equivalent to the arsenic beam current used in the second molecular beam epitaxy system. If the As component of the InGaAsP epitaxial layer grown in both systems is y0, then the phosphorus beam current used in the first molecular beam epitaxy system is equivalent to the phosphorus beam current used in the second molecular beam epitaxy system. Since the phosphorus beam current in the first molecular beam epitaxy system has been calibrated, the calibration of the phosphorus beam current in the second molecular beam epitaxy system is achieved through the above method.

[0033] It should be understood that the calibrated molecular beam epitaxy system is in a relatively stable state within a certain period of time and does not need to be recalibrated repeatedly. If the molecular beam epitaxy system is used for too long (for example, the ion gauge measurement may deviate), or after the molecular beam epitaxy system is disassembled for maintenance or servicing, the arsenic beam current and the phosphorus beam current need to be recalibrated. Therefore, the first molecular beam epitaxy system and the second molecular beam epitaxy system described in this application can refer to different molecular beam epitaxy devices, or can refer to the same molecular beam epitaxy device at different times. As mentioned above, only the initial calibration of the phosphorus beam current needs to be carried out by means of multiple attempts, and the relevant test data for the growth of the InGaAsP epitaxial layer are obtained. Subsequently, whether it is the calibration of the phosphorus beam current after the maintenance of the same device or the calibration of the phosphorus beam current of other devices, the method of this application can be used for the rapid calibration of the phosphorus beam current.

[0034] In summary, the present application determines the relative size relationship between the arsenic beam and the phosphorus beam actually required in the epitaxial growth process in different systems by growing InGaAsP materials with fixed In and As components in different molecular beam epitaxy systems, and then uses the arsenic beam calibration data and the relative size relationship to realize the phosphorus beam calibration of the new molecular beam epitaxy system. This method is efficient and reliable and can significantly save time and material costs.

[0035] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable ordinary technicians in the field to understand the content of the present invention and implement it. They cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for calibrating a phosphorus beam in a molecular beam epitaxy system, characterized in that: The method comprises: In a first molecular beam epitaxy system where the phosphorus beam current has been calibrated, on a first InP substrate, an In x0 Ga 1-x0 As y0 P 1-y0 epitaxial layer is grown at a preset growth temperature with a preset thickness. Let x0 represent the component of In among the group III elements and y0 represent the component of As among the group V elements, and 0.53 < x0 < 1, 0 < y0 < 1. During the growth of the In x0 Ga 1-x0 As y0 P 1-y0 epitaxial layer, the phosphorus beam current is a preset first beam current, and the arsenic beam current is a preset second beam current. By selecting the value of x0, the In x0 Ga 1- x0 As y0 P 1-y0 epitaxial layer is lattice-matched to the InP substrate. In the first molecular beam epitaxy system, when the surface reconstruction RHEED pattern of a GaAs material of a preset specification changes from a As-rich (2×4) stripe to a Ga-rich (4×2) stripe during molecular beam epitaxy at a preset fixed temperature and a preset Ga beam current, the corresponding arsenic beam current is the third beam current; In a second molecular beam epitaxy system to be calibrated for phosphorus beam flow, an InP substrate having a preset thickness is grown on a second InP substrate having the same specifications as the first InP substrate at the preset growth temperature. x0 Ga 1-x0 As y P 1-y The epitaxial layer is grown by adjusting the phosphorus beam current to different values. x0 Ga 1-x0 As y P 1-y The growth of the epitaxial layer finally makes the As component y actually measured equal to y0, and the value of the phosphorus beam current corresponding to the As component y equal to y0 is used as the calibrated phosphorus beam current of the second molecular beam epitaxy system. In the second molecular beam epitaxy system, the GaAs material of the preset specification is transformed from the As-rich (2×4) stripes to the Ga-rich (4×2) stripes at the preset fixed temperature and the preset Ga beam during the molecular beam epitaxy process. The corresponding arsenic beam current is the fourth beam current. x0 Ga 1-x0 As y P 1-y During the epitaxial layer growth process, the arsenic beam current is the fifth beam current, and the fifth beam current = (fourth beam current / third beam current) × second beam current, The value range of the second beam current is from one fifth of the third beam current to twice of the third beam current. The value range of the first beam current is 2 to 3 times of the minimum phosphorus beam current required for growing an InP epitaxial layer on an InP substrate in the first molecular beam epitaxy system, and the growth rate of In when growing the InP epitaxial layer is the same as that when growing the InP epitaxial layer. x0 Ga 1-x0 As y0 P 1-y0 The growth rate of In in the epitaxial layer is the same.

2. The method for calibrating phosphorus beam in a molecular beam epitaxy system according to claim 1, characterized in that: The value of the second beam current is equal to the third beam current.

3. The method for calibrating phosphorus beam in a molecular beam epitaxy system according to claim 1, characterized in that: The preset thickness ranges from 200 nm to 600 nm.

4. The method for calibrating phosphorus beam in a molecular beam epitaxy system according to claim 3, characterized in that: The preset thickness ranges from 300 nm to 400 nm.

Images