Multilayer substrate

Abstract

A substrate is provided having a silicon layer and an optically polished silicon-diamond interface. [Solution] A laminate substrate includes a silicon layer having an optically finished surface and a chemical vapor deposition (CVD) grown diamond layer on the optically finished surface of the silicon layer. The interface between the silicon layer and the diamond layer is such that the optically finished surface of the silicon layer has a surface roughness (Ra) of 100 nm or less. The surface of the grown diamond layer opposite the silicon layer is polished to an optical finish, and a light management coating can be applied to the surface of the grown diamond layer opposite the silicon layer. Methods of forming the laminate substrate are also disclosed.

Description

Technical Field

[0001] The present invention relates to a substrate having a silicon layer and an optically finished silicon-diamond interface, a diamond layer, and, optionally, a diamond surface that is optically finished. The present invention further relates to a method of making the substrate and describes the applications of the substrate.

Background Art

[0002] Diamond is known as one of the hardest materials with a Mohs hardness of 10 and is most useful for applications such as cutting, drilling, boring, milling, etc. Diamond also has the highest thermal conductivity of up to 2000-2200 W / (m·K) and is a desirable material for temperature management applications under severe conditions. Diamond also has an extremely low coefficient of friction and is a versatile material for applications such as brakes. Using diamond on diamond results in a low coefficient of friction and is advantageous for lubrication applications under harsh conditions. Diamond is also a desirable optical material for transmitting microwave, infrared, visible light, and other ultraviolet electromagnetic waves. Diamond also has high stability when used as a detector for high fluence nuclear radiation. Moreover, diamond is a very inert material even in a chemical environment that may contain strong acids, strong bases, strong oxidizing agents, or strong reducing agents, even under high or extremely low temperature conditions. Furthermore, diamond has a high refractive index, leading to its use in the gemstone industry.

[0003] Moreover, as shown in Table 1 below, the speed of sound in diamond is 18,500 m / s. ​​​​​​​​​​​​​Yes. This is even faster than the speed of sound in single-crystal silicon (8,500 m / s) and silicon carbide (13,300 m / s). The speed of sound is a property inherent to the material that is considered when manufacturing an elastic wave resonator. Elastic wave resonators are widely used as RF filters, RF oscillators, RF MEM S switches, and microsystems (sensors). The resonant frequency of the elastic wave resonator is directly proportional to the speed of sound of the material and inversely proportional to the geometric dimensions of the resonator. The resonator made of diamond (having a specific geometric shape) resonates at a frequency 2.2 times that of a resonator made of silicon. Therefore, for a specific resonant frequency, the resonator made of diamond can have geometric dimensions that are 2.2 times smaller than those of a resonator made of silicon. The diamond resonator has lower energy loss during vibration compared to a silicon resonator. The energy loss is measured by the quality factor Q. While the theoretical Q value of silicon is about 36,000, the theoretical Q value of diamond is about 380,000. The higher the Q value, the lower the energy loss during vibration.

[0004]

Table 1

[0005] Therefore, it is desirable for the diamond elastic wave resonator to have both high-quality diamond and a high-quality diamond surface, which facilitates the realization of products with high resonant frequencies, high Q values (or low energy losses due to low power consumption), or high-frequency Q.

[0006] ​​​​Industrially, diamond can be grown in a reactor by a method called chemical vapor deposition (CVD). Suitable growth conditions can be achieved by microwave-enhanced plasma, tungsten thermal filament, DC jet plasma, laser-induced plasma, acetylene torch, etc. Achievable.

[0007] In many diamond applications, the surface of the substrate containing diamond is used as an elastic wave medium or as a substrate that reflects light / electromagnetic waves, or for the purpose of removing thermal energy from electronics, photonics or optoelectronics through a specific type of bonding such as soldering or adhesion, it needs to be polished optically smooth. Since diamond is known as one of the hardest materials, polishing diamond is a time-consuming and costly process, in which the substrate containing diamond is subjected to stress and at the same time heat is generated. Furthermore, diamond is brittle and easy to grind. The heat and stress generated during the polishing of the diamond film cause delamination or partial delamination of the diamond film layers constituting the substrate. Causing. Summary of the Invention Problems to be Solved by the Invention

[0008] Regarding the coefficient of thermal expansion, there is a large mismatch between diamond (about 1×10 -6 m / m-K) and silicon (about 3×1 0 -6 m / m-K). Diamond films are generally grown on silicon substrates at high temperatures. At the end of the diamond film growth process, the substrate containing the diamond layer and the silicon layer is cooled from the diamond growth temperature to room temperature. is cooled. Diamond has a much smaller shrinkage than silicon, which can cause a large stress between the diamond layer and the silicon layer. At that time, the diamond is subjected to compressive stress and the silicon is subjected to tensile stress. Such a stress due to the mismatch in the coefficient of thermal expansion increases with the geometric dimensions of the substrate including the diamond layer and the silicon layer. When the said stress reaches a specific level, the diamond layer can be peeled off from the silicon layer. Often, the peeled diamond layer is crushed into many uneven small pieces due to the compressive stress, or the silicon layer, such as a silicon wafer, breaks due to the tensile stress. .

Means for Solving the Problem

[0009] The substrate disclosed herein has an optically finished silicon-diamond interface (or a diamond particle density of 10 9 / cm 2 or more of a dense diamond-silicon interface), and a silicon layer having an optically finished diamond surface if necessary, and a diamond layer. The surface roughness (Ra) of the diamond surface at the silicon-diamond interface can be 100 nm or less, 50 nm or less, 30 nm or less, 20 n m or less, 10 nm or less, or 5 nm or less. The surface roughness of the silicon surface at the silicon-diamond interface can be 100 nm or less, 50 nm or less, 30 nm or less , 20 nm or less, 10 nm or less, 5 nm or less, 2 nm or less, or 1 nm or less. The surface roughness of the said diamond layer on the side opposite to the interface can be 100 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, 10 nm or less, or 5 nm or less. The substrate The thickness of the diamond layer is 5 microns or less, 10 microns or less, 20 microns or less , 50 microns or less, 100 microns or less, 200 microns or less, 500 microns or less, or may be 2,000 microns or less. The thickness of the silicon layer of the substrate is 10 microns or more, 50 microns or more, 100 microns or more, 200 microns or more, 500 microns or more, 2,000 microns or more, or 5,000 microns or more. The diameter of the substrate is 1 inch (25.4 mm) or more, 2 inches (50.8 mm) or more, 3 inches (76. 2 mm) or more, 4 inches (101.6 mm) or more, 5 inches (127 mm) or more, or 6 inches (152.4 mm) or more. The overall thickness of the substrate is 50 microns or more, 100 microns or more, 150 microns or more, 250 microns or more, 500 microns or more, 1 mm or more, 3 mm or more, or 5 mm or more.

[0010] The diamond layer can be doped or undoped polycrystalline, nanocrystalline, or ultrananocrystalline . The silicon layer can be doped or undoped polycrystalline, single crystal, etc. The diamond quality can have a Raman peak full-width at half-maximum of 20 cm -1 or less, 15 cm -1 or less, 10 cm -1 or less, or 7 cm - 1 or less.

[0011] Growth conditions for making the substrate including an optically finished silicon-diamond interface (or a dense diamond-silicon interface), and, optionally, an optically finished diamond surface, are also disclosed herein.

Brief Description of the Drawings

[0012]

Figure 1

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DETAILED DESCRIPTION OF THE INVENTION

[0013] Various non-limiting examples will be described with reference to the accompanying drawings. The same reference numerals in the figures correspond to the same or functionally equivalent elements.

[0014] With respect to FIG. 1, in one embodiment, the composite substrate 2 includes a silicon layer 4 and a diamond layer 6 , and the interface 8 between the silicon layer and the diamond layer is optically finished or can be physically dense with substantially no voids or gaps between diamond particles. Specifically, the diamond surface 10 at the silicon-diamond interface 8 can be optically finished (characterized by removing the silicon layer 4 to expose the diamond interface surface), or can be physically dense with substantially no voids or gaps between diamond particles. The surface roughness (Ra) of the diamond surface 10 at the silicon-diamond interface (for an optically finished interface) can be 100 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, 10 nm or less, or 5 nm or less. For a silicon surface that is lapped, ground, or etched at the interface, the diamond-silicon interface can be characterized by the presence of voids or gaps between diamond particles that can be characterized by the diamond particle density. The particle density of diamond is 1 (characterized by removing the silicon layer 4 to expose the diamond interface surface), or can be physically dense with substantially no voids or gaps between diamond particles. The surface roughness (Ra) of the diamond surface 10 at the silicon-diamond interface (for an optically finished interface) can be 100 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, 10 nm or less, or 5 nm or less. For a silicon surface that is lapped, ground, or etched at the interface, the diamond-silicon interface can be characterized by the presence of voids or gaps between diamond particles that can be characterized by the diamond particle density. The particle density of diamond is 1 state. The surface roughness (Ra) of the diamond surface 10 at the silicon-diamond interface (for an optically finished interface) can be 100 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, 10 nm or less, or 5 nm or less. For a silicon surface that is lapped, ground, or etched at the interface, the diamond-silicon interface can be characterized by the presence of voids or gaps between diamond particles that can be characterized by the diamond particle density. The particle density of diamond is 1 or less, 30 nm or less, 20 nm or less, 10 nm or less, or 5 nm or less. For a silicon surface that is lapped, ground, or etched at the interface, the diamond-silicon interface can be characterized by the presence of voids or gaps between diamond particles that can be characterized by the diamond particle density. The particle density of diamond is 1 silicon interface can be characterized by the presence of voids or gaps between diamond particles that can be characterized by the diamond particle density. The particle density of diamond is 1 can be characterized by the presence of voids or gaps between diamond particles. The particle density of diamond is 1 can be characterized by the presence of voids or gaps between diamond particles. The particle density of diamond is 1 0 4 / cm 2 Above, 10 5 / cm 2 Above, 10 6 / cm 2 Above, 10 7 / cm 2 Above, 1 0 8 / cm 2 Above or 10 9 / cm 2 It can be the above. At the silicon-diamond interface The surface roughness (Ra) of the silicon surface (for optically finished silicon) at the silicon-diamond interface is 1 00 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, 10 nm or less, 5 nm or less , 2 nm or less or 1 nm or less. The surface roughness Ra of the silicon surface at the silicon-diamond interface 8 is determined by the roughness of the same silicon surface before diamond growth.

[0015] In the application of the substrate 2 in the elastic wave resonator, the dense layer of diamond at the silicon-diamond interface enables the elastic wave to propagate with minimal scattering. Otherwise the elastic wave will attenuate in the porous medium.

[0016] The optically finished silicon-diamond interface also enables precise control of the geometric dimensions of the resonator and, similarly, controls the characteristic elastic resonance frequency (critical value such as in an RF communication filter or transmitter).

[0017] In the application of the substrate 2 in optical wave management, the dense layer of diamond at the silicon interface avoids light scattering, and the optically finished surface enables precise control of light reflection, refraction, and conduction. In the application of the substrate 2 in temperature management, at the silicon-diamond interface ​​​​The densely packed diamonds therein avoid the delay of heat conduction in air and utilize the fast phonon propagation in the diamond medium to achieve high-performance temperature management.

[0018] If necessary, the diamond surface 14 of the substrate 2 (on the opposite side of the silicon-diamond interface 8) can be optically finished. The optically finished diamond surface 14 can be achieved by a polishing process. The surface roughness (Ra) of the diamond surface 14 can be 100 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, 10 nm or less, or 5 nm or less. The optical finishing of the diamond surface 14 is due to optical management for light control, temperature management for coupling to a heat source, precise control of geometric dimensions, and elastic wave management for creating piezoelectric and electrode structures to achieve desired elastic wave resonance control and performance.

[0019] The silicon surface 16 of the substrate 2 (on the opposite side of the silicon-diamond interface 8) having an optically finished (or densely packed) interface, and the diamond surface 14 optically finished if necessary, can be ground, etched, or optically polished.

[0020] In one embodiment, the diamond layer 6 of the substrate 2 can have any thickness. In one embodiment, the thickness of the diamond layer 6 can be 5 microns or less, 10 microns or less, 20 microns or less, 50 microns or less, 100 microns or less, 200 microns or less, 500 microns or less, or 2,000 microns or less. In one embodiment, the thickness of the diamond layer 6 is related to elastic waves. It can be determined by the accuracy required in resonance, light propagation control, and / or temperature management efficiency. It can be determined.

[0021] In one embodiment, the silicon layer 4 of the substrate 8 can have any thickness. In one embodiment, the thickness can be 10 microns or more, 50 microns or more, 100 microns or more, 200 microns or more, 500 microns or more, 2,000 microns or more, or 5,000 microns or more. The thickness of the silicon layer can be determined by the requirements and practical necessities during the process of manufacturing the substrate 2.

[0022] The substrate 2 can have any geometric (maximum) dimension. In one embodiment, the maximum dimension (e.g., diameter) can be 1 inch (25.4 mm) or more, 2 inches (50.8 mm) or more, 3 inches (76.2 mm) or more, 4 inches (101.6 mm) or more, 5 inches (127 mm ) or more, or 6 inches (152.4 mm) or more. The diameter of the substrate 2 can be selected and controlled so that it can be handled by different manufacturing methods.

[0023] The substrate 2 can have a thickness of 50 microns or more, 100 microns or more, 150 microns or more, 250 mic rons or more, 500 microns or more, 1 mm or more, 3 mm or more, or 5 mm or more. The thickness of the substrate can be determined by a manufacturing method that meets the requirements in a specific application. It can be determined.

[0024] The diamond layer 6 of the substrate 2 has a non-doped or doped p-type quality with a Raman peak full width at half maximum of 20 cm -1 or less, 15 cm -1 or less, 10 cm -1 or less, or 7 cm -1 or less. It can be of n-type. The diamond layer 6 can be polycrystalline, nanocrystalline or ultrananocrystalline. The doped conductive diamond layer 6 can be used in a capacitive drive elastic resonance device. The doped conductive diamond layer 6 can be used as an electrode material for a high-Q resonance medium for elastic wave management. The quality of the diamond layer 6 can also be selected to achieve a desired level of intrinsic elastic velocity and low power loss in elastic resonance. The quality of the diamond layer 6 affects light wave absorption and thermal conductivity and is determined by the requirements in optical and thermal applications. The quality of the diamond layer 6 can also be selected to achieve a desired level of intrinsic elastic velocity and low power loss in elastic resonance. The quality of the diamond layer 6 affects light wave absorption and thermal conductivity and is determined by the requirements in optical and thermal applications. The quality of the diamond layer 6 affects light wave absorption and thermal conductivity and is determined by the requirements in optical and thermal applications.

[0025] The silicon layer 4 of the substrate 2 can be undoped or doped p-type or n-type single crystal or polycrystal. In the case of single crystal silicon, the silicon layer 4 can be cut from any crystal direction. The type of silicon constituting the silicon layer 4 can also be selected for elastic wave management. In one embodiment, a high electrical resistance silicon layer 4 may be required. In other embodiments, a conductive silicon layer 4 may be required. Finally, in other embodiments, a single crystal or polycrystalline silicon layer may be required. In the case of single crystal silicon, the silicon layer 4 can be cut from any crystal direction. The type of silicon constituting the silicon layer 4 can also be selected for elastic wave management. In one embodiment, a high electrical resistance silicon layer 4 may be required. In other embodiments, a conductive silicon layer 4 may be required. Finally, in other embodiments, a single crystal or polycrystalline silicon layer may be required. In other embodiments, a conductive silicon layer 4 may be required. Finally, in other embodiments, a single crystal or polycrystalline silicon layer may be required. In other embodiments, a single crystal or polycrystalline silicon layer may be required.

[0026] The growth of the diamond layer 6 on the substrate 2 can be carried out by any diamond growth process including microwave plasma enhanced chemical vapor deposition (CVD), DC arc jet plasma CVD process, thermal filament CVD process, laser induced plasma CVD process, acetylene torch CVD process, etc., but is not particularly limited. The growth of the diamond layer 6 on the substrate 2 can be carried out by any diamond growth process including microwave plasma enhanced chemical vapor deposition (CVD), DC arc jet plasma CVD process, thermal filament CVD process, laser induced plasma CVD process, acetylene torch CVD process, etc., but is not particularly limited. The growth of the diamond layer 6 on the substrate 2 can be carried out by any diamond growth process including microwave plasma enhanced chemical vapor deposition (CVD), DC arc jet plasma CVD process, thermal filament CVD process, laser induced plasma CVD process, acetylene torch CVD process, etc., but is not particularly limited. The growth of the diamond layer 6 on the substrate 2 can be carried out by any diamond growth process including microwave plasma enhanced chemical vapor deposition (CVD), DC arc jet plasma CVD process, thermal filament CVD process, laser induced plasma CVD process, acetylene torch CVD process, etc., but is not particularly limited.

[0027] The substrate 2 has an aspect ratio of 5 or more, 10 or more, 15 or more, 20 or more, or 30 or more. It is possible. The aspect ratio is defined as the ratio of the longest or largest geometric dimension (e.g., diameter) of the substrate 2 to the thickness of the substrate 2. In one embodiment, the larger the aspect ratio of the substrate 2, particularly due to the limitations in the manufacturing method and the level of mismatch in the coefficient of thermal expansion between the diamond 6 and silicon 4 materials, it becomes difficult to fabricate the substrate 2. The greater the aspect ratio of the substrate 2, particularly due to the limitations in the manufacturing method and the level of mismatch in the coefficient of thermal expansion between the diamond 6 and silicon 4 materials, it becomes difficult to fabricate the substrate 2.

[0028] A method for manufacturing a substrate 2 having an optically finished (or dense) silicon-diamond interface 8 and, if necessary, an optically finished diamond surface 14 includes a silicon layer 4 and a diamond layer 6, as shown in the flowchart of FIG. 2.

[0029] Regarding FIG. 2, in step S1, the surface 12 of the silicon substrate 4 (for diamond film growth) can be ground or lapped, chemically etched, or optically polished using a chemical mechanical polishing slurry. In step S2, ultrasonic treatment of the silicon layer 4 using a slurry made of diamond powder and a liquid medium (e.g., water, methanol, ethanol, isopropanol, or any liquid medium), or seeding the silicon surface 12 with conventional diamond powder (having a particle size of submicron to several tens of microns) by light friction that does not form deep surface scratches can be performed. The seeding can also be achieved by bias-enhanced seeding method.

[0030] Next, in step S3, the silicon substrate 4 can be placed inside a CVD growth system (e.g., the CVD reactor schematically shown in FIG. 3). In step S4, the diamond growth process can be started. In step S8, small ​​​​​​​​​​​​​​ Until the preferred thickness and density of the diamond crystal are achieved, the diamond growth process can be continued.

[0031] When the preferred thickness and density of diamond growth are achieved, in step S9, the growth of the diamond layer 6 is stopped, and the substrate 2 including the silicon layer 4 and the diamond layer 6 is removed from the CVD growth system. In steps S10 and S11, the growth surface of the diamond layer 6 is optionally lapped (S10) and optionally polished (S11) for optical finishing. Since steps S10 and S11 are optional, these steps can be omitted as desired. If steps S10 and S11 are omitted, the manufacturing method of the substrate 2 can proceed directly from step S9 to step S12 as shown by the dashed line 18 in FIG. 2. As shown in step S12, the substrate 2 including the silicon layer 4 and the diamond layer 6 has an optically finished silicon-diamond interface. The substrate 2 can further have a dense diamond-silicon interface with substantially no voids or gaps between the diamond particles. Finally, the substrate 2 can optionally have an optically finished diamond (nucleation) surface 14.

[0032] As shown in FIG. 2, the manufacturing method of the substrate 2 can also include steps S5 to S7 during steps S4 to S8. In step S5, the CVD diamond growth process can be stopped as needed, and the substrate 2 including a part of the diamond layer 6 CVD-grown on the silicon layer 4 in step S4 can be removed from the CVD growth system. In step S6, ​​​​​​​​​​​​​​​A part of the diamond layer 6 CVD-deposited on the silicon layer 4 can be reseeded or further seeded with nanodiamond powder.

[0033] In step S7, the substrate 2 including a part of the diamond layer 6 reseeded with nanodiamond powder in step S6 can be returned to the CVD growth system. A part of the further diamond layer 6 can grow on the seeded part of the already grown diamond layer 6.

[0034] Steps S5 to S7 are optional, so these steps can be omitted as necessary. Assuming that steps S5 to S7 are omitted, as shown by the dashed line 20 in FIG. 2, the method can proceed directly from step S4 to S8.

[0035] Chemical vapor deposition of diamond by microwave plasma is well known in the art. FIG. 3 is a schematic diagram showing an example of a microwave plasma CVD growth system 102 that can be used to grow a diamond layer 6 on a silicon layer 4. In the use of the CVD growth system 102, the silicon layer 4 is first placed on a substrate holder 122 at the bottom of a CVD reactor 116 of the CVD growth system 102. Then , a mixture of reactive gas 106 containing hydrogen and methane is introduced into the CVD reactor 116 . The flow rate of the mixture of reactive gas 106 is adjusted by a mass flow controller 108 . The exhaust gas 110 flows from the CVD reactor 116 mainly to a vacuum pump 112 . Microwave energy is mainly generated by a microwave source 114 such as a magnetron, etc. and is introduced into the CVD reactor 116 through a quartz window 118. The CVD reactor​​​ Within 116, the microwave energy is converted into plasma 120, and the reactive gas 1 06 hydrogen molecules are converted into hydrogen free radicals. Similarly, the methane molecules of the reactive gas 106 are converted into meth yl free radicals, methylene free radicals, methine free radicals, and secondary or tertiary free radicals containing two or more carbons are radicalized. At the bottom of the CVD reactor 116 is placed a substrate holder or base 122 that first supports the silicon layer 4 on which the diamond layer 6 grows or pedestal.

[0036] During the generation of plasma 120, the radicalized free radicals containing carbon species collide with the surface of the silicon layer 4 and lead to the deposition of carbon species by a mechanism called "hit and stick". After an appropriate length of time in the presence of plasma 120, the diamond layer 6 grows to an appropriate thickness.

[0037] The concentrations of hydrogen and methane in the mixed gas of the reactive gas 106 are parameters that affect diamond growth in addition to the growth temperature (which can be measured by the optical pyrometer 126 ). It is well known in the art. Desirably, the size of the plasma 120 is adjusted to a size large enough to cover the upward surface of the silicon layer 4. The microwave energy and the pressure in the CVD reactor 116 depend on the substrate size. Those skilled in the art should be able to adjust the plasma 120 to an appropriate size large enough to cover silicon layers 4 of different sizes for the purpose of growing high-quality diamond films 6 . This first seeding step (S2 in FIG. 2) is for the good growth of the diamond film 6 on the silicon substrate 4

[0038] ​​​​ Promote achieving good adhesion. In the first seeding step (S2 in FIG. 2), diamond at the silicon-diamond interface leads to some cavities or gaps between diamond particles. Generally, cavities or gaps between diamond particles at the silicon-diamond interface are not desirable for high-frequency and high-Q (low energy loss) elastic wave resonators, or for controllable optical management (low scattering), effective temperature management (high heat transfer). To help avoid the formation of cavities or gaps at the silicon-diamond interface, the process shown in FIG. 2 can optionally include a second step of diamond seeding (S5 - S7 in FIG. 2). In the second step of diamond seeding, after stopping the diamond growth process, the silicon substrate from the first step is taken out of the reactor. Subsequently, the silicon substrate is reseeded using one or more nanodiamond slurries and ultrasonic treatment. Such a nanodiamond slurry can be made with a nanodiamond powder together with a liquid medium, such as water, methanol, ethanol, isopropanol, or any inorganic / organic liquid medium. Then, the silicon substrate seeded with nanodiamond can be returned to the CVD growth system (reactor). Subsequently, the diamond growth process is restarted on the silicon substrate seeded with nanodiamond (S8 in FIG. 2). Nanodiamond seeding leads to the formation of an optically finished silicon-diamond interface (if an optically finished silicon substrate is used) or a dense silicon-diamond interface, resulting in a silicon layer 4 and diamond grown without the second diamond seeding step (S5 - S7). ​​​​​​​​Reduce the cavities or gaps on the substrate 2 including the diamond layer 6. Then, the diamond film growth (S8 in FIG. 2) continues in the CVD growth system until the desired thickness of the diamond film 6 is achieved.

[0039] In one embodiment, the one-step diamond seeding process using nanodiamond powder alone results in weak adhesion of the diamond film 6 to the optically finished silicon substrate 4. Moreover, delamination or partial delamination of the diamond film 6 was observed after the CVD growth system was stopped or during polishing when large heat and stress were applied to the substrate 2 including the diamond layer 6 and the silicon layer 4. These adhesion and delamination problems become more significant as the diameter of the substrate 2 increases.

[0040] The two-step diamond seeding process described above avoids delamination of the diamond layer 6 from the silicon layer 4 and enables a stronger bond at the silicon-diamond interface 8 that can withstand the heat and stress resulting from subsequent diamond surface polishing. At the same time, when using a silicon layer 4 with an optically finished surface 12, an optically finished silicon-diamond interface can be achieved for the substrate 2 and, if necessary, the optically finished diamond growth surface 14.

[0041] When using a silicon surface 12 that is ground / lapped or chemically etched, the diamond nucleation surface 10 at the silicon-diamond interface 8 becomes densely packed with a minimum of cavities or gaps between the diamond particles. This results in a density of 10 / cm at the silicon-diamond interface 8. 4 / cm​​​​​​​​​2 10 or more 5 / cm 2 10 or more 6 / cm 2 or more 10 7 / cm 2 10 or more 8 / cm 2 or more or 10 9 / cm 2 diamond grain density as described above is demonstrated by. After removing the substrate 2 from the CVD reactor 116, the diamond growth surface 14 is optionally lapped (S10 in FIG. 2) and optionally polished optically (S11 in FIG. 2) so that the thickness of the silicon layer 4 can be reduced to a desired thickness. The embodiments described herein use a silicon layer 4 whose one dimension (diameter) can be increased. The thermal expansion coefficient of silicon is about 3×10 m / m-K, while that of diamond is about 1×10

[0042] m / m-K. Furthermore, diamond mainly grows at high temperatures. During the stop of CVD diamond growth, the temperature generally drops from the diamond growth temperature to room temperature. The mismatch in the thermal expansion coefficients between the diamond layer 6 and the silicon layer 4 leads to a large stress between the diamond layer 6 and the silicon layer 4. This can become severe as the dimension of the silicon layer 4 increases. Moreover, unlike metal substrates such as tungsten and molybdenum, silicon is brittle and cannot withstand the initiation of plasma during the CVD growth of the diamond layer 6 on the silicon layer 4. In one embodiment, silicon wafers ( with a diameter of 6 inches (152.4 mm) and a thickness of 625 microns) were tested as the silicon layer 4 for diamond growth. Unfortunately, these silicon wafers were unable to withstand the CVD reactor -6 during the start of plasma. m / m-K. -6 m / m-K. grows. During the stop of CVD diamond growth, the temperature generally drops from the diamond growth temperature to room temperature. The mismatch in the thermal expansion coefficients between the diamond layer 6 and the silicon layer 4 leads to a large stress between the diamond layer 6 and the silicon layer 4. This can become severe as the dimension of the silicon layer 4 increases. Moreover, unlike metal substrates such as tungsten and molybdenum, silicon is brittle and cannot withstand the initiation of plasma during the CVD growth of the diamond layer 6 on the silicon layer 4. In one embodiment, silicon wafers ( with a diameter of 6 inches (152.4 mm) and a thickness of 625 microns) were tested as the silicon layer 4 for diamond growth. Unfortunately, these silicon wafers were unable to withstand the CVD reactor during the start of plasma. This can become severe as the dimension of the silicon layer 4 increases. Moreover, unlike metal substrates such as tungsten and molybdenum, silicon is brittle and cannot withstand the initiation of plasma during the CVD growth of the diamond layer 6 on the silicon layer 4. In one embodiment, silicon wafers ( with a diameter of 6 inches (152.4 mm) and a thickness of 625 microns) were tested as the silicon layer 4 for diamond growth. Unfortunately, these silicon wafers were unable to withstand the CVD reactor during the start of plasma. with a diameter of 6 inches (152.4 mm) and a thickness of 625 microns) were tested as the silicon layer 4 for diamond growth. Unfortunately, these silicon wafers were unable to withstand the CVD reactor during the start of plasma. Within 116, it was ground every time at the initial stage of the tuning process of the plasma 120. A thick piece of It was observed that only the silicon layer 6 remained during the plasma startup tuning process. In one embodiment In, the silicon layer 4 that can withstand the plasma startup tuning process has a thickness of 1 mm or more, 2 mm or more, 4 mm or more, 6 mm or more, or 8 mm or more.

[0043] As shown in FIG. 1, the silicon layer (wafer) 4 is, for example, combined with other substrates such as a silicon substrate, a graphite substrate, a metal substrate, a ceramic substrate, or a glass substrate using a bonding reagent 15. By bonding onto a thicker substrate 17, the silicon layer 4 can withstand plasma startup without being ground, or bent or "potato chip" deformed at the central part.

[0044] The bonding reagent 15 can include a polymer, a carbon-based material, a silicate or silicate-based material, for example, a metal-based material such as silver, gold , platinum, nickel, or copper.

[0045] The silicon layer 4 and / or the diamond layer 6 of the substrate 2 can be, for example, etched away and partially removed. When the silicon layer 4 is partially removed, the diamond surface 10 at the silicon-diamond interface 8 can be exposed. Such a diamond surface 1 0 can have a high density with a minimum or no voids or gaps between diamond particles. . If the silicon surface 12 is optically finished, the diamond surface 10 at the silicon-diamond interface 8 can also have an optical finish with a surface roughness Ra of 100 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, 10 nm or less, or 5 nm or less. It can be cut.

[0046] In other embodiments, the diamond layer 6 can be used as a substrate or a window. The dia The diamond layer 6 can have a 1.06 micron light scattering coefficient of 20 / cm or less, 15 / cm or less, 10 / cm or less, 7 / cm or less, or 5 / cm or less (at a distance of 34 cm from the shielding lens), and may be suitable for optical applications, temperature management applications, elasticity management applications, etc. .

[0047] In other embodiments, the diamond layer 6 is 1.0×10 5 / cm 2 or more, 1.0×10 6 / cm 2 or more, 1.0×10 7 / cm 2 or more, 1.0×10 8 / cm 2 or more, or 1.0× 10 9 / cm 2 or more in diamond nucleation density, and may also be suitable for elastic wave propagation for elasticity management, phonon propagation for temperature management, and photon propagation for optical management. The above-mentioned diamond nucleation density may also be suitable for mechanical applications. The diamond nucleation can result in a diamond film 6 with low porosity due to chemical inertness and properties favorable for surface friction control. In other embodiments, while the diamond layer 6 is on the silicon layer 4, the as-grown diamond surface 14 can be polished. In this case, the total thickness of the diamond layer 6 and the silicon layer 4 is sufficient for a conventional polishing process to hold and polish the substrate 2 without grinding the diamond layer 6 during the polishing process. After achieving an optical finish on the surface 14 of the diamond layer 6, the substrate 2 is between . During the polishing process, the total thickness of the diamond layer 6 and the silicon layer 4 is sufficient to hold and polish the substrate 2 without grinding the diamond layer 6. After achieving an optical finish on the surface 14 of the diamond layer 6, the substrate 2 is Etching (on the silicon layer 4 side) can be carried out. At the end of this process, optically finished (or densified) silicon-diamond interface 8 and, if necessary, optically finished diamond surface 14, a thin piece of the substrate 2 including the silicon layer 4 and the diamond layer 6 can be fabricated.

[0048] In other embodiments, after fabricating the substrate 2 having the optically finished (or densified) silicon-diamond interface 8 and, if necessary, optically finished diamond surface 14, one or more optical management coatings 19 such as an antireflection coating, a beam splitter coating, a total reflection coating, etc., or, together with a specific type of electrode layer for elastic wave management, a layer of a piezoelectric material can also be applied to any exposed surface on the surface 14 of the diamond layer 6 as shown in, for example, FIG. 1. Such a substrate 2 can also be further cut into different geometric dimensions for various applications.

[0049] The diamond layer 6 of the substrate 2 can have an optical quality with low electromagnetic wave absorption having an absorbance of 0. 5 / cm or less, such as infrared rays, near-infrared light, ultraviolet light, or UV light. In microwave applications, it can also have a low dielectric tangent, such as a dielectric tangent of 1×10 -2 . Also, it can be a mechanical and / or thermal grade diamond (dark in color and having a thermal conductivity exceeding, for example, 800 W / m -K). It can also be a detector grade diamond (having a charge collection distance of 1 00 microns or more) or an electrochemical grade diamond (requiring, for example, doping with boron). ​​​​​​

[0050] The diamond layer 6 of the substrate 2 is formed by a microwave-assisted plasma CVD process, a thermal filament CVD process, a thermal spray CVD process, an arc discharge plasma CVD process, a direct current thermal plasma CVD process, a high-frequency plasma CVD process, a water plasma CVD process, an acetylene torch CVD process, an ultra-high frequency plasma CVD process, etc. It can be grown by CVD.

[0051] The growth temperature of the diamond layer 6 of the substrate 2 can be set to 600°C to 1300°C. The growth rate of the diamond layer 6 can be set to sub-micron / hour to 20 microns / hour. The methane concentration of the reactive gas 106 for growing the diamond layer 6 can be in the range from less than 1% to 5% in hydrogen. Other additives of the reactive gas 106 can include oxygen, carbon monoxide, carbon dioxide, nitrogen, boron, etc. These other reactive gas additives can be added for diamond growth rate control and / or diamond quality control.

[0052] The silicon layer 4 for growing the diamond layer 6 has a diameter of 30 mm or more, 2 inches (50 .8 mm) or more, 66 mm or more, 3 inches (76.2 mm) or more, 4 inches (101.6 mm) or more, 5 inches (127 mm) or more, or 6 inches (152.4 mm) or more.

[0053] The thickness of the silicon layer 4 of the substrate 2 can be 1 mm or more, 2 mm or more, 4 mm or more, 6 mm or more or 8 mm or more.

[0054] The surface of the silicon layer 4 of the substrate 2 can be optically finished, chemically etched, and / or mechanically finished, for example, lapped and / or polished. The surface roughness Ra of the optically finished surface 16 can be 20 nm or less, 15 nm or less, 10 nm or less, 5 nm or less, or 2 nm or less.

[0055] In other embodiments, the silicon surface 12 can optionally include a thin layer of a dielectric film 13, such as, for example, SiO 2 , SiN, or one or more other dielectric layers. The substrate can be silicon-on-insulator (SOI). The dielectric film 13 can be of any thickness. In one embodiment, the dielectric film 13 has a thickness suitable for supporting the diamond film 6 to achieve a specific function, for example, as an elastic wave resonator for elastic wave management. In one embodiment, the thickness of the dielectric film 13 can be a few angstroms to 100 microns, 1 nm to 50 microns, 10 nm to 20 microns, or 50 nm to 10 microns.

[0056] Each of the composite substrates 2 of various embodiments of the diamond layer 6 and the silicon layer 4 can be used for one or more of the following applications. Optical applications for light / electromagnetic wave management Substrate 2 for temperature management applications in electronics, photonics, or optoelectronics Substrate 2 for use with chemical inertness Substrate 2 for fabricating an elastic wave resonator including a surface and / or bulk elastic wave resonator RF filter, RF transmitter, RF MEMS switch, or MEMS sensor Friction control Detector​​​​​​​ and / or materials for mechanical use such as, for example, milling, cutting, drilling, grooving, etc. materials

[0057] The following examples and comparative examples are for explaining the main elements and should not be construed as being limited to the following examples.

[0058] <Evaluation method> Scanning electron microscope (SEM) images were obtained using a Tescan Vega scanning electron microscope equipped with an energy-dispersive X-ray (EDAX) detector.

[0059] Raman spectra were obtained using a Renishaw Raman microscope (confocal). Laser Raman spectroscopy is widely used as a standard for the evaluation of diamond, single crystal or polycrystal. It provides distinguishable features for each of the different forms (allotropes) of carbon (e.g., diamond, graphite, buckyballs, etc.). By combining photoluminescence (PL) technology, a non-destructive method for evaluating various properties of diamond, including phase purity, crystal size and orientation, defect level and structure, impurity species and concentration, and stress and strain, is provided. In particular, the full width at half maximum FWHM of the primary diamond Raman peak at 1332 cm is a direct indicator of diamond quality, as is the Raman intensity ratio between the diamond peak and the graphite peak (the D band at 1350 cm and the G band at 1600 cm -1 . Furthermore, the stress and strain levels of diamond particles and films can be estimated from the diamond Raman peak shift. The rate of diamond Raman peak shift under hydrostatic pressure is about 3.2 cm -1 and the G band at 1600 cm -1 ). ​​-1 is in GPa and under tensile stress has been reported to shift its peak to a lower wavenumber under tensile stress and to a higher wavenumber under compressive stress. Here the Raman spectrum represented was obtained using an inVia Raman spectrometer of Renishaw equipped with a 514 nm excitation laser.

[0060] The surface roughness (Ra) and Peak-to-Valley (PV) measurements on the surface of a polished piece of diamond were obtained by a Zygo NewView6000 interferometer equipped with a 20x objective lens. The measurement area was 200 microns × 350 microns.

[0061] The optical scattering coefficient for 1.064 micron wavelength light was measured using a Nd-YAG solid 1.064 micron wavelength laser and determined by the ratio of the scattered light intensity collected at a distance of 34 mm from the sample (while the transmitted light was blocked) to the total light intensity including the transmitted light (i.e., without blocking the transmitted light).

[0062] Example 1: Method for manufacturing a thin diamond substrate having one optically finished surface A piece of a single crystal silicon substrate 4 with a diameter of 66 mm and a thickness of 11.5 mm was manufactured using a general silicon manufacturing method. The surface 12 of this silicon substrate 4 was diamond cut so as to be an optically finished surface with Ra of 6 - 7 nm. At the same time, the logo "II-VI" was also cut in a recessed manner by diamond cutting on the surface 12 of this silicon substrate 4. Then, the silicon substrate 4 was used as a substrate in a microwave plasma CVD reactor 116 (Figure 3) with the diamond cut optically finished surface (surface 12) facing the direction in which the plasma 120 was formed. ​

[0063] A mixture of 1,850 mL / min of hydrogen and 13.6 mL / min of methane was flowed into the microwave plasma CVD reactor 116. After the start of plasma irradiation, the magnitude of the plasma 120 was adjusted such that the microwave energy and the reactor pressure covered the surface 12 of the silicon substrate 4. The diamond growth temperature at the central portion of the surface 12 of the silicon substrate 4 was controlled at 800 °C, for example, using a pyrometer 126. After 168 hours of diamond growth, the reaction was stopped. A polycrystalline diamond layer 6 with a thickness of 285 microns was deposited conformally on the surface 12 of the silicon layer 4. Next, the silicon substrate 4 was etched using an aqueous KOH solution at a high temperature, and then etched using HF-HNO to obtain a single piece of a self-standing diamond film having a diameter of 66 mm, a thickness of 285 microns, and an aspect ratio of 231. The nucleation surface 10 of the diamond layer 6 was measured to have a surface roughness (Ra) of 9.1 nm. 3 ratio of 231. The nucleation surface 10 of the diamond layer 6 was measured to have a surface roughness (Ra) of 9.1 nm.

[0064] FIG. 4(a) is an image of this self-standing diamond layer 6, which is optically transparent on the finish surface on the growth side 14, and a "II-VI" logo grown conformally on the diamond-cut grooves on the silicon surface 12. This indicates that any non-planar surface in a single piece of diamond can be obtained by growing diamond conformally on the "negative" surface of a sacrificial substrate (e.g., silicon layer 4) that can be manufactured by conventional manufacturing methods such as diamond cutting processes, as well as optical manufacturing methods that may include polishing, lapping, ion etching and / or chemical mechanical polishing. In one embodiment, the non-planar nuclei ​​​​​​​​​​​The surface of the grown diamond is an optical finish. Figure 4(b) is an enlarged view of the nucleation side 10 of the self-standing diamond layer 6 shown in Figure 4(a). Figure 4(c) is an enlarged view of the nucleation side 14 of the self-standing diamond layer 6 shown in Figure 4(a). The second piece of the single-crystal silicon substrate 4 with a diameter of 66 mm and a thickness of 11.5 mm was manufactured by a general silicon manufacturing method. The surface 12 of this silicon substrate 4 was also diamond cut so as to be an optically finished surface with Ra of 6 to 7 nm. Then, the surface 12 of this silicon substrate 4 was ultrasonically treated using a diamond ethanol suspension slurry. Next, this silicon substrate 4 was used as the substrate of the microwave plasma CVD reactor 116 (Figure 3) with the optically finished surface (surface 12) diamond cut facing the direction in which the plasma 120 is formed. A mixture of 1,850 mL / min of hydrogen and 13.6 mL / min of methane was flowed into the microwave plasma CVD reactor 116. After the start of plasma irradiation, the microwave energy and the reactor pressure were adjusted so that the size of the plasma 120 covered the surface 12 of the silicon substrate 4. The diamond growth temperature at the center of the surface 12 of the silicon substrate 4 was controlled at 800 °C by, for example, the optical pyrometer 126. After 148 hours of diamond growth, the reaction was stopped. A polycrystalline diamond layer 6 with a thickness of 233 microns was deposited conforming to the surface 12 of the silicon layer 4. Next, the silicon substrate 4 was stripped using an aqueous KOH solution at a high temperature, and then stripped with HF-HNO

[0065] The second piece of the single-crystal silicon substrate 4 with a diameter of 66 mm and a thickness of 11.5 mm was manufactured by a general silicon manufacturing method. The surface 12 of this silicon substrate 4 was also diamond cut so as to be an optically finished surface with Ra of 6 to 7 nm. Then, the surface 12 of this silicon substrate 4 was ultrasonically treated using a diamond ethanol suspension slurry. Next, this silicon substrate 4 was used as the substrate of the microwave plasma CVD reactor 116 (Figure 3) with the optically finished surface (surface 12) diamond cut facing the direction in which the plasma 120 is formed. The second piece of the single-crystal silicon substrate 4 with a diameter of 66 mm and a thickness of 11.5 mm was manufactured by a general silicon manufacturing method. The surface 12 of this silicon substrate 4 was also diamond cut so as to be an optically finished surface with Ra of 6 to 7 nm. Then, the surface 12 of this silicon substrate 4 was ultrasonically treated using a diamond ethanol suspension slurry. Next, this silicon substrate 4 was used as the substrate of the microwave plasma CVD reactor 116 (Figure 3) with the optically finished surface (surface 12) diamond cut facing the direction in which the plasma 120 is formed. The second piece of the single-crystal silicon substrate 4 with a diameter of 66 mm and a thickness of 11.5 mm was manufactured by a general silicon manufacturing method. The surface 12 of this silicon substrate 4 was also diamond cut so as to be an optically finished surface with Ra of 6 to 7 nm. Then, the surface 12 of this silicon substrate 4 was ultrasonically treated using a diamond ethanol suspension slurry. Next, this silicon substrate 4 was used as the substrate of the microwave plasma CVD reactor 116 (Figure 3) with the optically finished surface (surface 12) diamond cut facing the direction in which the plasma 120 is formed. The second piece of the single-crystal silicon substrate 4 with a diameter of 66 mm and a thickness of 11.5 mm was manufactured by a general silicon manufacturing method. The surface 12 of this silicon substrate 4 was also diamond cut so as to be an optically finished surface with Ra of 6 to 7 nm. Then, the surface 12 of this silicon substrate 4 was ultrasonically treated using a diamond ethanol suspension slurry. Next, this silicon substrate 4 was used as the substrate of the microwave plasma CVD reactor 116 (Figure 3) with the optically finished surface (surface 12) diamond cut facing the direction in which the plasma 120 is formed. The second piece of the single-crystal silicon substrate 4 with a diameter of 66 mm and a thickness of 11.5 mm was manufactured by a general silicon manufacturing method. The surface 12 of this silicon substrate 4 was also diamond cut so as to be an optically finished surface with Ra of 6 to 7 nm. Then, the surface 12 of this silicon substrate 4 was ultrasonically treated using a diamond ethanol suspension slurry. Next, this silicon substrate 4 was used as the substrate of the microwave plasma CVD reactor 116 (Figure 3) with the optically finished surface (surface 12) diamond cut facing the direction in which the plasma 120 is formed. The second piece of the single-crystal silicon substrate 4 with a diameter of 66 mm and a thickness of 11.5 mm was manufactured by a general silicon manufacturing method. The surface 12 of this silicon substrate 4 was also diamond cut so as to be an optically finished surface with Ra of 6 to 7 nm. Then, the surface 12 of this silicon substrate 4 was ultrasonically treated using a diamond ethanol suspension slurry. Next, this silicon substrate 4 was used as the substrate of the microwave plasma CVD reactor 116 (Figure 3) with the optically finished surface (surface 12) diamond cut facing the direction in which the plasma 120 is formed. The second piece of the single-crystal silicon substrate 4 with a diameter of 66 mm and a thickness of 11.5 mm was manufactured by a general silicon manufacturing method. The surface 12 of this silicon substrate 4 was also diamond cut so as to be an optically finished surface with Ra of 6 to 7 nm. Then, the surface 12 of this silicon substrate 4 was ultrasonically treated using a diamond ethanol suspension slurry. Next, this silicon substrate 4 was used as the substrate of the microwave plasma CVD reactor 116 (Figure 3) with the optically finished surface (surface 12) diamond cut facing the direction in which the plasma 120 is formed.

[0066] A mixture of 1,850 mL / min of hydrogen and 13.6 mL / min of methane was flowed into the microwave plasma CVD reactor 116. After the start of plasma irradiation, the microwave energy and the reactor pressure were adjusted so that the size of the plasma 120 covered the surface 12 of the silicon substrate 4. The diamond growth temperature at the center of the surface 12 of the silicon substrate 4 was controlled at 800 °C by, for example, the optical pyrometer 126. After 148 hours of diamond growth, the reaction was stopped. A polycrystalline diamond layer 6 with a thickness of 233 microns was deposited conforming to the surface 12 of the silicon layer 4. Next, the silicon substrate 4 was stripped using an aqueous KOH solution at a high temperature, and then stripped with HF-HNO A mixture of 1,850 mL / min of hydrogen and 13.6 mL / min of methane was flowed into the microwave plasma CVD reactor 116. After the start of plasma irradiation, the microwave energy and the reactor pressure were adjusted so that the size of the plasma 120 covered the surface 12 of the silicon substrate 4. The diamond growth temperature at the center of the surface 12 of the silicon substrate 4 was controlled at 800 °C by, for example, the optical pyrometer 126. After 148 hours of diamond growth, the reaction was stopped. A polycrystalline diamond layer 6 with a thickness of 233 microns was deposited conforming to the surface 12 of the silicon layer 4. Next, the silicon substrate 4 was stripped using an aqueous KOH solution at a high temperature, and then stripped with HF-HNO A mixture of 1,850 mL / min of hydrogen and 13.6 mL / min of methane was flowed into the microwave plasma CVD reactor 116. After the start of plasma irradiation, the microwave energy and the reactor pressure were adjusted so that the size of the plasma 120 covered the surface 12 of the silicon substrate 4. The diamond growth temperature at the center of the surface 12 of the silicon substrate 4 was controlled at 800 °C by, for example, the optical pyrometer 126. After 148 hours of diamond growth, the reaction was stopped. A polycrystalline diamond layer 6 with a thickness of 233 microns was deposited conforming to the surface 12 of the silicon layer 4. Next, the silicon substrate 4 was stripped using an aqueous KOH solution at a high temperature, and then stripped with HF-HNO A mixture of 1,850 mL / min of hydrogen and 13.6 mL / min of methane was flowed into the microwave plasma CVD reactor 116. After the start of plasma irradiation, the microwave energy and the reactor pressure were adjusted so that the size of the plasma 120 covered the surface 12 of the silicon substrate 4. The diamond growth temperature at the center of the surface 12 of the silicon substrate 4 was controlled at 800 °C by, for example, the optical pyrometer 126. After 148 hours of diamond growth, the reaction was stopped. A polycrystalline diamond layer 6 with a thickness of 233 microns was deposited conforming to the surface 12 of the silicon layer 4. Next, the silicon substrate 4 was stripped using an aqueous KOH solution at a high temperature, and then stripped with HF-HNO A mixture of 1,850 mL / min of hydrogen and 13.6 mL / min of methane was flowed into the microwave plasma CVD reactor 116. After the start of plasma irradiation, the microwave energy and the reactor pressure were adjusted so that the size of the plasma 120 covered the surface 12 of the silicon substrate 4. The diamond growth temperature at the center of the surface 12 of the silicon substrate 4 was controlled at 800 °C by, for example, the optical pyrometer 126. After 148 hours of diamond growth, the reaction was stopped. A polycrystalline diamond layer 6 with a thickness of 233 microns was deposited conforming to the surface 12 of the silicon layer 4. Next, the silicon substrate 4 was stripped using an aqueous KOH solution at a high temperature, and then stripped with HF-HNO A mixture of 1,850 mL / min of hydrogen and 13.6 mL / min of methane was flowed into the microwave plasma CVD reactor 116. After the start of plasma irradiation, the microwave energy and the reactor pressure were adjusted so that the size of the plasma 120 covered the surface 12 of the silicon substrate 4. The diamond growth temperature at the center of the surface 12 of the silicon substrate 4 was controlled at 800 °C by, for example, the optical pyrometer 126. After 148 hours of diamond growth, the reaction was stopped. A polycrystalline diamond layer 6 with a thickness of 233 microns was deposited conforming to the surface 12 of the silicon layer 4. Next, the silicon substrate 4 was stripped using an aqueous KOH solution at a high temperature, and then stripped with HF-HNO A mixture of 1,850 mL / min of hydrogen and 13.6 mL / min of methane was flowed into the microwave plasma CVD reactor 116. After the start of plasma irradiation, the microwave energy and the reactor pressure were adjusted so that the size of the plasma 120 covered the surface 12 of the silicon substrate 4. The diamond growth temperature at the center of the surface 12 of the silicon substrate 4 was controlled at 800 °C by, for example, the optical pyrometer 126. After 148 hours of diamond growth, the reaction was stopped. A polycrystalline diamond layer 6 with a thickness of 233 microns was deposited conforming to the surface 12 of the silicon layer 4. Next, the silicon substrate 4 was stripped using an aqueous KOH solution at a high temperature, and then stripped with HF-HNO A mixture of 1,850 mL / min of hydrogen and 13.6 mL / min of methane was flowed into the microwave plasma CVD reactor 116. After the start of plasma irradiation, the microwave energy and the reactor pressure were adjusted so that the size of the plasma 120 covered the surface 12 of the silicon substrate 4. The diamond growth temperature at the center of the surface 12 of the silicon substrate 4 was controlled at 800 °C by, for example, the optical pyrometer 126. After 148 hours of diamond growth, the reaction was stopped. A polycrystalline diamond layer 6 with a thickness of 233 microns was deposited conforming to the surface 12 of the silicon layer 4. Next, the silicon substrate 4 was stripped using an aqueous KOH solution at a high temperature, and then stripped with HF-HNO 3 The second piece of the single-crystal silicon substrate 4 with a diameter of 66 mm and a thickness of 11.5 mm was manufactured by a general silicon manufacturing method. The surface 12 of this silicon substrate 4 was also diamond cut so as to be an optically finished surface with Ra of 6 to 7 nm. Then, the surface 12 of this silicon substrate 4 was ultrasonically treated using a diamond ethanol suspension slurry. Next, this silicon substrate 4 was used as the substrate of the microwave plasma CVD reactor 116 (Figure 3) with the optically finished surface (surface 12) diamond cut facing the direction in which the plasma 120 is formed. A single piece of a self - standing diamond film with a ratio of 283 was obtained. Nucleation of the diamond layer 6 The surface 10 was measured to have a surface roughness (Ra) of 11.5 nm.

[0067] The quality of this latter diamond film 6 was evaluated by Raman spectroscopy. As shown in Fig. 5 As shown, the diamond crystals on the growth side 14 have a Raman shift center of 1331.9 - 1 332.1 cm -1 and, together with a narrow FWHM of 2.8 cm -1 (compared with the FWHM of 3.5 cm of a single - crystal diamond piece), as proven by this, are of excellent quality, suggesting that there is no stress in the diamond film on the growth side. The diamond crystals on the nucleation side also have a FWHM of 3.8 - 4.1 cm and a Raman peak at a center of 1331.6 cm -1 -1 -1

[0068] and are very excellent (indicating low stress in the diamond film on the nucleation side).

[0068] Example 2: Manufacture of a thin diamond substrate or window having one or two optically finished surfaces A single piece of a single - crystal silicon substrate (or layer) 4 with a diameter of 2 inches (50.8 mm) and a thickness of 10 mm was manufactured using a general silicon manufacturing method. Both surfaces of this silicon substrate 4 were optically finished to an Ra of less than 1 nm by a general chemical - mechanical polishing process. Then

[0069]

[0069]

[0069] A mixture of 1,850 mL / min of hydrogen and 13.6 mL / min of methane was flowed into the microwave plasma CVD reactor 116. After the start of plasma 120 irradiation, the microwave energy and reactor pressure were adjusted so that the size of the plasma 120 covered the surface 12 of the silicon substrate 4. The diamond growth temperature at the central part of the surface 12 of the silicon substrate 4 was controlled to 800 °C, for example, using the pyrometer 126. After 140 hours of diamond growth , the reaction was stopped, and a polycrystalline diamond film 6 with a thickness of 200 - 220 microns deposited conformally on the surface 12 of the silicon substrate 4 was obtained. Then, the diamond growth surface 14 was lapped while the diamond layer 6 was still on the silicon substrate 4 and polished to a surface roughness of Ra5.0 nm. After lapping and polishing, the thickness of the diamond layer 6 on the silicon substrate 4 was 125 microns. Then, the silicon layer 4 was etched off using a hot KOH aqueous solution, and subsequently etched off with HF - HNO to obtain a single piece of free - standing diamond film 6 with a diameter of 2 inches (50.8 mm), a thickness of 125 microns, and an aspect ratio of 406. Both surfaces of the free - standing diamond film 6 were optically finished and can be applied as a substrate for optical windows or other uses. A second piece of a single - crystal silicon substrate (or layer) 4 with a diameter of 2 inches (50.8 mm) and a thickness of 10 mm was fabricated using a general silicon manufacturing method. Both surfaces 12 and 16 of this silicon substrate 4 were optically finished to less than 1 nm Ra by a general chemical - mechanical polishing process. Then, this silicon substrate 4 was polished with a diamond - methanol suspension slurry 3 and then etched off with HF - HNO to obtain a single piece of free - standing diamond film 6 with a diameter of 2 inches (50.8 mm), a thickness of 125 microns, and an aspect ratio of 406. Both surfaces of the free - standing diamond film 6 were optically finished and can be applied as a substrate for optical windows or other uses. Both surfaces of the free - standing diamond film 6 were optically finished and can be applied as a substrate for optical windows or other applications.

[0070] A second piece of a single - crystal silicon substrate (or layer) 4 with a diameter of 2 inches (50.8 mm) and a thickness of 10 mm was fabricated using a common silicon manufacturing method. The two surfaces 12 and 16 of this silicon substrate 4 were optically finished to less than 1 nm Ra by a common chemical - mechanical polishing process. Then, this silicon substrate 4 was polished with a diamond - methanol suspension slurry ​​​​​It was ultrasonically treated. Next, this silicon substrate 4 was introduced into the microwave plasma CVD reactor 116 with the surface 12 facing in the direction where the plasma 120 was formed. A mixture of 2,700 mL / min of hydrogen and 16.2 mL / min of methane was flowed into the microwave plasma CVD reactor 116. After the start of plasma irradiation, the microwave energy and the reactor pressure were adjusted so that the size of the plasma 120 covered the surface 12 of the silicon substrate 4.

[0071] A mixture of 2,700 mL / min of hydrogen and 16.2 mL / min of methane was flowed into the microwave plasma CVD reactor 116. After the start of plasma irradiation, the microwave energy and the reactor pressure were adjusted so that the size of the plasma 120 covered the surface 12 of the silicon substrate 4. The diamond growth temperature at the central part of the surface 12 was controlled between 832 °C and 866 °C, for example, using a pyrometer 126. After 72 hours of diamond growth, the reaction was stopped, and a polycrystalline diamond film 6 with a thickness of 110 - 130 microns deposited conformally on the surface 12 of the silicon layer 4 was obtained. The diamond growth temperature at the central part of the surface 12 was controlled between 832 °C and 866 °C, for example, using a pyrometer 126. After 72 hours of diamond growth, the reaction was stopped, and a polycrystalline diamond film 6 with a thickness of 110 - 130 microns deposited conformally on the surface 12 of the silicon layer 4 was obtained. After 72 hours of diamond growth, the reaction was stopped, and a polycrystalline diamond film 6 with a thickness of 110 - 130 microns deposited conformally on the surface 12 of the silicon layer 4 was obtained. Then, the diamond growth surface 14 was lapped while the diamond layer 6 was still on the silicon substrate 4 and polished to a surface roughness (Ra) of 5.8 nm. After lapping and polishing, the thickness of the diamond layer 6 on the silicon substrate 4 was 60 - 70 microns. Then, the diamond growth surface 14 was lapped while the diamond layer 6 was still on the silicon substrate 4 and polished to a surface roughness (Ra) of 5.8 nm. After lapping and polishing, the thickness of the diamond layer 6 on the silicon substrate 4 was 60 - 70 microns. Then, the silicon layer 4 was etched off using an aqueous KOH solution at a high temperature, and then etched off with HF - HNO to obtain a single piece of a free - standing diamond film 6 with a diameter of 2 inches, a thickness of 60 - 70 microns, and an aspect ratio of 781. 3 to obtain a single piece of a free - standing diamond film 6 with a diameter of 2 inches, a thickness of 60 - 70 microns, and an aspect ratio of 781. Both surfaces of the free - standing diamond film 6 were optically finished and can be applied as an optical window or a substrate for other applications. Both surfaces of the free - standing diamond film 6 were optically finished and can be applied as an optical window or a substrate for other applications. Both surfaces of the free - standing diamond film 6 were optically finished and can be applied as an optical window or a substrate for other applications.

[0072] The third piece of a single - crystal silicon substrate (or layer) 4 with a diameter of 2 inches (50.8 mm) and a thickness of 10 mm was manufactured using a general silicon manufacturing method. Both surfaces of this silicon substrate 4 were 12 and 16 were optically finished to an Ra of less than 1 nm by a general chemical mechanical polishing process. Then, this silicon substrate 4 was polished optically by rubbing with a 0.25 micron diamond slurry and subsequently a general cleaning process was performed. Next, this silicon substrate 4 was rubbed with diamond slurry and the optically finished surface 12 was oriented in the direction in which the plasma 120 was to be formed and introduced into the microwave plasma CVD reactor 116.

[0073] A mixture of 2,700 mL / min of hydrogen and 16.2 mL / min of methane was flowed into the microwave plasma CVD reactor 116. After the start of plasma 120 irradiation, the microwave energy and reactor pressure were adjusted so that the size of the plasma 120 covered the surface 12 of the silicon substrate 4. The diamond growth temperature at the central portion of the surface 12 was controlled, for example, using a pyrometer 126 to 794 - 835 °C. After 95 hours of diamond growth, the reaction was stopped and a polycrystalline diamond film 6 with a thickness of 156 microns deposited conformally on the surface 12 of the silicon substrate 4 was obtained. The obtained diamond film 6 (by removing the silicon layer 4) had an aspect ratio of 326. As is common for as - grown diamond surfaces, the surface roughness of the nucleation side 10 was 7.7 nm and the surface of the growth side 14 of the diamond film 6 was rough.

[0074] Example 3: Diamond Growth on One Piece of a 166 mm × 10 mm Single - Crystal Si Substrate with Chemically Etched Both Surfaces, Fabrication of a Thin Diamond Substrate with One Optically Finished Surface One piece of a single - crystal silicon substrate 4 with a diameter of 166 mm and a thickness of 10 mm was a general silicon - made ​​​​​​​Both surfaces 12 and 16 of the silicon substrate 4 were fabricated using a conventional chemical process. The silicon substrate 4 is then polished with diamond powder. The mixture was then rubbed with a cloth and placed in a microwave plasma CVD reactor 116.

[0075] A mixture of 2,800 mL / min of hydrogen and 84 mL / min of methane was heated in a microwave oven. The plasma CVD reactor 116 was then filled with the gas. After the plasma 120 started to be irradiated, the size of the plasma The microwave energy and reactor pressure are adjusted to cover the surface 12 of the silicon substrate 4. The diamond growth temperature at the center of the surface 12 was measured, for example, using a photometric pyrometer 126. After 44 hours of diamond growth, the reaction was stopped and the silicon A polycrystalline diamond film having a thickness of 350 microns is deposited conformally on the surface 12 of the silicon substrate 4. A composite substrate 2 including a film 6 was obtained. The diamond growth surface 14 was still covered with diamond. The diamond was then lapped flat while still on the silicon substrate 4. The thickness of the diamond-on-silicon film 6 was 300 microns. The exposed silicon surface 16 of one piece of substrate 2 is 1.7 to 1. It was lapped until it was .8mm thick.

[0076] The lapped diamond surface 14 is then further polished to an optical finish and A thin diamond film (i.e., 300 mm thick) is formed on a silicon substrate 4 with a diameter of 166 mm. The composite substrate 2 is used for optical mirrors or electronic It can be used as a substrate for semiconductors, photonics or optoelectronics. Next, the silicon substrate 4 was peeled off, and a free-standing thin diamond film 6 having a polished growth surface with an aspect ratio of 533 or more was produced.

[0077] Before removing the silicon substrate 4, in order to polish the diamond growth surface 14, one piece with a diameter of 50 mm and a plurality of pieces with a diameter of 1 inch were laser cut from the diamond-on-silicon composite substrate 2. The roughness of the growth surface 14 of the 50 mm piece reached 1 nm, and the thickness of the polished diamond layer 6 was estimated to be 170 - 180 microns. Then, the silicon substrate 4 was peeled off using an aqueous KOH solution at high temperature, and subsequently peeled off with HF-HNO, and a free-standing diamond film 6 with a diameter of 50 mm, a thickness of 175 microns, and an aspect ratio of 285 was obtained. This diamond growth surface 14 was optically polished and can be used as a substrate for optical mirrors or other applications such as thermal management. Alternatively, in order to remove the silicon substrate 4, the silicon substrate 4 was thinned and the surface 16 was polished to obtain a piece of the diamond-silicon composite substrate 2 having at least the optically polished diamond surface 14. 3

[0078] It was polished with an ind powder and introduced into the microwave plasma CVD reactor 116.

[0079] A mixture of 2,800 mL / min of hydrogen and 84 mL / min of methane was flowed into the microwave plasma CVD reactor 116. After the start of plasma 120 irradiation, the size of the plasma was adjusted so that the microwave energy and the reactor pressure covered the surface 12 of the silicon substrate 4. The diamond growth temperature at the central part of the surface 12 was controlled at 1120 °C, for example, using a photometric pyrometer 126. After 24 hours of diamond growth, the reaction was stopped, and a polycrystalline diamond film 6 with a thickness of 175 microns deposited conformally on the surface 12 of the silicon substrate 4 was obtained. The diamond growth surface 14 was flatly lapped while the diamond was still on the silicon substrate 4. The lapped diamond growth surface 14 was further polished and optically finished. Then, the silicon substrate 4 was peeled off using an aqueous KOH solution at a high temperature, and then peeled off with HF-HNO to obtain a free-standing diamond film 6 with a diameter of 166 mm, a thickness of less than 175 microns, and an aspect ratio of 948. This diamond growth surface 14 was optically finished and can be used as a substrate for an optical mirror or other applications such as, for example, thermal management. Alternatively, in order to remove the silicon substrate 4, the silicon substrate 4 (while the diamond layer 6 is still attached) was thinned as necessary, and the surface 16 was polished to obtain at least a diamond surface 14 that was optically finished. 3 A piece of a diamond-silicon composite substrate 2 was obtained and can be used as a substrate for an optical mirror or for electronics, photonics, or optoelectronics. ​​​​​​​​

[0080] Example 5: One surface optically finished by chemical mechanical polishing process (Ra: 1.3 nm Diamond growth on a piece of 166 mm × 10 mm polycrystalline Si substrate with a thin Fabrication of diamond windows or substrates having one or both optically finished surfaces The piece of polycrystalline silicon substrate 4 with a diameter of 166 mm and a thickness of 10 mm is made of ordinary silicon. Both surfaces 12 and 16 of the silicon substrate 4 were fabricated using a conventional chemical process. The surface 12 was then polished using a chemical mechanical polishing process. Then, one side of the silicon substrate 4 was polished and optically finished (Ra: 1.3 nm). The piece is ultrasonically treated with an aqueous diamond slurry and then the surface 12 is plasma 120 The mixture was then fed into the microwave plasma CVD reactor 116 in the direction in which the mixture was formed.

[0081] A mixture of 2,800mL / min of hydrogen and 16.8mL / min of methane was After the start of the plasma 120 irradiation, the size of the plasma The microwave energy and reactor pressure are adjusted so that the surface 12 of the silicon substrate 4 is covered. The diamond growth temperature at the center of the surface 12 was measured, for example, by a photometric pyrometer 126. The temperature was controlled at 846-868°C using a tungsten carbide (Teflon) ... The polycrystalline silicon substrate 4 was deposited to a thickness of 295 microns on the surface 12 of the silicon substrate 4. The diamond film 6 was obtained. The diamond growth surface 14 was still covered with the diamond layer 6. The diamond was then lapped flat while still on the silicon layer 4. The diamond surface 14 is then polished to an optical finish, forming a diamond having an aspect ratio of 563. The diamond layer 6 was obtained.

[0082] The silicon layer 4 side of this diamond-silicon composite substrate 2 was polished to a total thickness of 1.7 to 2 .0 mm. Then, the diamond-silicon composite substrate 2 was laser-cut into pieces with a diameter of 1 inch (25.4 mm) and a diameter of 85 mm. Subsequently, the growth surface 14 of the diamond layer 6 was optically polished to obtain an optically finished surface with a diamond layer 6 thickness of 150 microns or less.

[0083] In one embodiment, the silicon layer 4 was stripped using an aqueous KOH solution at high temperature, followed by HF-HN O 3 to strip, and a free-standing diamond layer 6 with a diameter of 1 inch (25.4 mm) and 85 mm, a thickness of 150 microns or less , and an aspect ratio of 566 was obtained. The diamond growth surface 1 4 was optically finished and can be used as a substrate for an optical mirror or other applications such as thermal management. Alternatively, to remove the silicon substrate 4, the silicon substrate 4 ( with the diamond layer 6 still attached) was thinned, and the surface 16 was polished to obtain a diamond-silicon composite substrate 2 having at least an optically finished diamond surface 14, which can be used as an optical mirror or a substrate for electronics, photonics, or opto electronics.

[0084] Comparative Example 1: Failure of diamond growth on a silicon wafer (diameter 6 inches, thickness 625 microns) Three silicon substrates or wafers 4 (n-type, diameter 6 inches (152.4 mm), thickness 625 microns) were prepared. The surface 12 of each silicon wafer 4 was chemically mechanically polished ​​​and finish on the optical surface, and the other surfaces 16 of each silicon wafer 4 are finished by chemical etching. Then, the surface 12 (optically finished) of each silicon wafer 4 was peeled off using diamond powder, and the silicon wafer 4 was placed in a microwave plasma CVD reactor 116 for diamond growth with the optically finished surface 12 facing the direction in which the plasma 120 is formed.

[0085] A mixture of 2,500 mL / min of hydrogen and 75 mL / min of methane was flowed into the microwave plasma CVD reactor 116. After the start of plasma 120 irradiation, the microwave energy and reactor pressure were adjusted so that the size of the plasma covered the surface 12 of the silicon wafer 4. During this plasma adjustment process, the silicon wafer 4 was pulverized into a number of small pieces. This experiment was repeated using two other silicon wafers 4 by changing the powder velocity and pressure increase, and similar results were obtained, that is, the other two silicon wafers were also pulverized into a number of small pieces.

[0086] Comparative Example 2: Failure to achieve optically finished diamond thinner than 400 microns Diamond pieces with diameters of 50 mm, 75 mm, 85 mm, and 100 mm were laser cut from as-grown diamond wafers with a thickness greater than 550 microns. In one example, this as-grown diamond wafer was directly grown on the substrate holder 122 of the microwave plasma CVD reactor 116 without having a silicon layer 4 between the as-grown diamond wafer and the substrate holder 122. Then, the growth surface of each diamond piece was flat lapped. Next, the growth surface or nucleus of these diamond pieces ​ One of the surfaces of the generated surface, i.e., one side, was polished by a conventional polishing process to be optically finished. When trying to polish the other surface thinly after turning it over, these diamond pieces were crushed before reaching a thickness of 400 microns. In the conventional diamond polishing process, it was suggested that it was difficult to achieve an aspect ratio of 125.

[0087] Example 6: Fabrication of a thin diamond coating on a silicon substrate having both optically finished surfaces A polycrystalline silicon substrate 4 with a diameter of 75 mm and a thickness of 10 mm was used as a substrate for the diamond CVD growth of the diamond layer 6. The surface 12 of this silicon substrate 4 was polished to a mirror finish with a roughness Ra of less than 1 nm. On the mirror-finished silicon surface 12, in order to achieve a high diamond nucleation density, while obtaining good adhesion between diamond and silicon to prevent the diamond layer from peeling off from this silicon substrate 4, a two-step seeding process was required. First, this silicon substrate 4 was treated in an ultrasonic bath using a diamond powder / methanol suspension with an average size of 0.25 μm. Then, the first step of performing a diamond nucleation process on the surface 12 was carried out on the silicon substrate 4 in a microwave plasma CVD reactor 116 for 1 hour. After that, the silicon substrate 4 was removed from the microwave plasma CVD reactor 116. This nucleation process resulted in a relatively low-density (10 5 / cm 2 less than full) diamond nucleation.

[0088] Figure 6 is an SEM photograph of the silicon surface after the first nucleation process.

[0089] Next, this silicon substrate 4 (after the first nucleus generation step) was treated with a nanocrystalline diamond powder / methanol suspension in an ultrasonic bath. Then, this silicon substrate 4 was placed back into the microwave plasma CVD reactor 116 for the second nucleus

[0090] generation step and continuous diamond growth on the silicon surface 12. To achieve this, a mixture of 2,400 mL / min of hydrogen and 16.8 mL / min of methane was flowed into the microwave plasma CVD reactor 116 during the first and second stages of the diamond nucleus generation process. After the start of plasma 120 irradiation, the microwave energy and reactor pressure were adjusted so that the size of the plasma covered the surface 12 of the silicon substrate 4. The diamond growth temperature at the central part of the surface 12 was controlled at 800 °C, for example, by using a pyrometer 126 and cooling the substrate holder 4. In the second nucleus generation step, after 14 hours of diamond growth, the reaction was stopped, and a polycrystalline diamond film 6 with a thickness of 20 μm deposited conformally on the surface 12 of the silicon substrate 4 was obtained. Then, while the diamond growth surface 14 was still on the silicon substrate 4, it was polished until the diamond film 6 had a surface roughness of 10 μm in thickness and an average Ra = 2.5 nm (shown in Figure 7). The surface roughness of the diamond nucleus generation side 10 at the silicon-diamond interface 8 was measured for another diamond sample formed using a similar two-step seeding process after the silicon was peeled off. The average surface roughness was measured to be an average Ra = 1.7 nm (shown in Figure 8). The diamond nucleus generation density was 10 / cm after the second nucleus generation step, as measured by SEM.

[0091] 9 9 9 / cm2 was evaluated to exceed (shown in Fig. 9). The flatness of the polished diamond growth surface 14 was observed by an optical interferometer. The diamond growth surface 14 had a height difference between peaks and valleys of 1.53 μm over the entire surface with a diameter of 75 mm, and the unevenness was 0.53 μm (shown in Fig. 10), and was determined to be slightly convex. and was observed over the entire surface with a diameter of 75 mm. The height difference between peaks and valleys of the diamond growth surface 14 was 1.53 μm, and the unevenness was 0.53 μm (shown in Fig. 10), and was determined to be slightly convex.

[0092] The diamond quality and phase purity were evaluated using a Raman spectrometer. Fig. 11 shows the Raman spectra obtained from (a) the as-grown diamond growth surface 14 and (b) the diamond growth surface 14 polished with a 514 nm excitation laser. The sharp diamond peak at 1332 cm with a peak width (FWHM) of 4. 3 - 6.2 cm was observed without detecting the sp -1 carbon signal, indicating that a high-quality diamond layer 6 was deposited on the silicon layer 4. A strong peak also appeared at 520 cm -1 , which is the silicon Raman peak 2 . This silicon peak originated from the silicon substrate or layer 4 under the diamond layer 6. was also observed at 520 cm -1 , which is the silicon Raman peak . This silicon peak originated from the silicon substrate or layer 4 under the diamond layer 6.

[0093] Example 7: Fabrication of a thin diamond coating on a silicon substrate having one optically finished surface A polycrystalline silicon substrate 4 with a diameter of 75 mm and a thickness of 10 mm was used as a substrate for diamond layer 6 diamond CVD growth. Both surfaces 12 and 16 of this silicon substrate 4 were chemically etched. Then, this silicon substrate 4 was treated using a nanocrystalline diamond powder / methanol suspension in an ultrasonic bath to promote diamond nucleation. Next, the silicon substrate was introduced into the microwave plasma CVD reactor 116.

[0094] A mixture of hydrogen at 2,400 mL / min and methane at 16.8 mL / min was flowed into the microwave plasma CVD reactor 116. After the start of plasma 120 irradiation, the microwave energy and the reactor pressure were adjusted so that the size of the plasma 120 covered the surface 12 of the silicon substrate 4 facing the plasma 120. The diamond growth temperature at the center of the surface 12 of the silicon substrate 4 facing the plasma 120 was controlled at 800 °C by cooling the substrate holder 122 using the photometric pyrometer 126. After 10 hours of diamond growth, the reaction was stopped, and a polycrystalline diamond film 6 with a thickness of 14 microns deposited conformally on the surface 12 of the silicon substrate 4 was obtained. The diamond growth surface 14 was polished until the diamond film 6 had a thickness of 8 microns and a surface roughness of an average Ra = 3.0 n m while still on the silicon substrate 4. Example 8: Diamond growth on a polycrystalline silicon substrate (166 mm in diameter, 10 mm thick) optically finished by 0.25 mm diamond powder seeding In other examples, a polycrystalline silicon substrate 4 with a diameter of 166 mm and a thickness of 10 mm was used as the substrate for CVD growth of the diamond layer 6. Both surfaces 12 and

[0095] 16 of this silicon substrate 4 were finished by a general chemical etching process. Then, the surface 12 of the silicon substrate 4 was chemically mechanically polished to a mirror finish with a roughness Ra of less than 1.5 nm. Next, the entire silicon substrate 4 was sonicated in an ultrasonic bath with diamond powder / metal of an average size of 0.25 μm In other examples, a polycrystalline silicon substrate 4 with a diameter of 166 mm and a thickness of 10 mm was used as the substrate for CVD growth of the diamond layer 6. Both surfaces 12 and 16 of this silicon substrate 4 were finished by a general chemical etching process. Then, the surface 12 of the silicon substrate 4 was chemically mechanically polished to a mirror finish with a roughness Ra of less than 1.5 nm. Next, the entire silicon substrate 4 was sonicated in an ultrasonic bath with diamond powder / metal of an average size of 0.25 μm and the surface 12 of the silicon substrate 4 was chemically mechanically polished to a mirror finish with a roughness Ra of less than 1.5 nm. Next, the entire silicon substrate 4 was sonicated in an ultrasonic bath with diamond powder / metal of an average size of 0.25 μm The surface 12 was sonicated (seeded) with a quartz window 118 (FIG. 3). ) in a CVD reactor 116 (FIG. 2).

[0096] A mixture of 2,800mL / min of hydrogen and 16.8mL / min of methane was fed into the mass flowmeter. The flow is controlled by the row controller 108 to the microwave plasma CVD reactor 116. After the start of the plasma 120 irradiation, the size of the plasma 120 increased to the surface 12 of the silicon substrate 4. The microwave 114 energy and the reactor 116 pressure were adjusted so as to cover the center of the substrate. The diamond growth temperature in the portion is measured, for example, at 845 to 860°C using a photometer 126. After 163 hours of diamond growth, the reaction was stopped and the silicon substrate was A polycrystalline die with a thickness of 295 μm and an aspect ratio of 563 was deposited conformally on surface 12 of the 4. Silicon-diamond composite substrates with diamond films 6 were obtained.

[0097] While the diamond film 6 is attached to the silicon substrate 4, the diamond film The growth surface of 6 is optically finished (Ra: 3-5 nm) and the thickness (diamond film 6 The diamond film 6 was polished to 99 microns and the aspect ratio was 168. During attachment to the contact substrate 4, the silicon-diamond composite substrate is etched into a number of layers having different diameters. After laser cutting into many different pieces, the silicon substrate 4 of each piece is removed (KOH solution) The diamond film was dissolved by the liquid, forming six free-standing diamond films. The nucleation surfaces of these pieces of bond film 6 have an average surface roughness (Ra) of 5–9 nm and a roughness of 10 5 / cm 2 These pieces of free-standing diamond film 6 had a nucleation density of 100 nm or more. One has a thickness of 99 microns and is characterized by a light scattering coefficient of 8.22 / cm and a light scattering wavelength of 1.06 μm at a distance of 34.0 mm from the scattered light collection lens. It is characterized in that it is.

[0098] Example 9: Diamond growth on an optically finished silicon substrate (2 inches in diameter ( 50.8 mm), 10 mm thick) by a first seeding step (0.25 mm diamond powder seeding) and a subsequent second seeding step ( nanodiamond powder seeding) In other examples, a polycrystalline silicon substrate 4 with a diameter of 50.8 mm and a thickness of 10 mm was used as a substrate for the CVD growth of a diamond layer 6. Both surfaces 1 2 and 16 of this silicon substrate 4 were chemically mechanically polished to a mirror finish with a roughness Ra of less than 1.5 nm. Next the entire silicon substrate 4 was ultrasonically treated (seeded) using a diamond powder / methanol suspension solution with an average size of 0.25 μm and placed in a CVD reactor 116 (Figure 3). Then this silicon substrate 4 was introduced into a microwave plasma CVD reactor 116.

[0099] A mixture of 2,800 mL / min of hydrogen and 16.8 mL / min of methane was adjusted by a mass flow controller 108 and flowed into the CVD reactor 116. After the start of plasma 12 0 irradiation, the microwave 114 energy and the reactor 116 pressure were adjusted so as to cover the surface 1 2 of the silicon substrate 4 facing the quartz window 118. The diamond growth temperature at the center of the silicon substrate 4 was controlled, for example, at 780 °C using a photometric pyrometer 126. After 1 hour of diamond growth, the reaction was stopped. The silicon substrate 4 seeded with diamond was covered with diamond powder deposited on the surface 12 of the silicon substrate 4. It was observed that

[0100] The diamond-seeded silicon substrate 4 is then removed from the CVD reactor 116 and subjected to Nanocrystalline diamond powder (typical particle size <20 nm) / methanol in an ultrasonic bath The suspension was then ultrasonically treated. The seeded silicon substrate is then placed in the CVD reactor 116 with the surface 12 again facing the plasma 120. A mixture of 2,800mL / min of hydrogen and 16.8mL / min of methane was added. is adjusted by a mass flow controller 108 to flow into the microwave plasma CVD reactor. After the plasma 120 started to be irradiated, the size of the plasma 120 became equal to that of the silicon substrate 4. The microwave 114 energy and reactor 116 pressure were adjusted to cover the surface 12 of The diamond growth temperature at the center of the silicon substrate 4 is measured, for example, by a photometer 126 The temperature was controlled between 790 and 821°C using a

[0101] After 143 hours of diamond growth, the diamond growth reaction was stopped and the thickness was reduced to 245 mm. Klon, Silicon-Diamond with Diamond Film 6 with Aspect Ratio of 207 The diamond growth surface was determined by the fact that the diamond layer 6 was still on the silicon substrate. While on the plate 4, it is optically finished (Ra 3-5 nm) and the thickness (diamond film 6) was polished to 197 microns with an aspect ratio of 258.

[0102] Next, the silicon substrate 4 is removed from the silicon-diamond composite substrate (using a KOH aqueous solution The diamond film was then dissolved using a fluorine-based solvent (HF) to leave a free-standing diamond film 6. The nucleation surface of the diamond film 6 had an average surface roughness (Ra) of 2.73 nm and a nucleation density of 10 9 / cm 2 or more, and had a smooth surface finish. Among these, the latter two are very suitable for applications such as, for example, heat management, optical management, semiconductor devices, friction control, elastic wave management, etc. This self-supporting diamond film 6 was characterized by having a light scattering coefficient of 2.69 / cm at a distance of 34.0 mm from the scattered light collection lens and a light scattering wavelength of 1.06 μm. The light scattering wavelength of 1.06 μm is considered low micron light scattering in the art and is very suitable for optical, thermal, acoustic applications, etc.

[0103] Example 10: Diamond growth on a silicon substrate (2 inches (50.8 mm) in diameter, 10 mm thick) optically finished by one-step seeding (nanodiamond powder seeding) In other examples, a polycrystalline silicon substrate 4 with a diameter of 50.8 mm and a thickness of 10 mm was used as a substrate for the CVD growth of the diamond layer 6. The surface 1 2 of this silicon substrate was chemically mechanically polished to a mirror finish with a roughness Ra of less than 1.5 nm. On the other hand, the other surface 16 was etched by a general chemical etching process. Next, this silicon substrate 4 was ultrasonically treated using a suspension solution of nanocrystalline diamond powder (general particle size less than 20 nm) / methanol. Then, this silicon substrate was introduced into the CVD reactor 116 with the surface 12 facing the quartz window 118.

[0104] A mixture of 2,800 mL / min of hydrogen and 16.8 mL / min of methane was adjusted by a mass flow controller 108 and flowed into the CVD reactor 116. Plasma 12 After the start of irradiation, the size of the plasma 120 is increased to cover the surface 12 of the silicon substrate 4. The microwave 114 energy and the reactor 116 pressure were adjusted. The diamond growth temperature was controlled at 800° C. using, for example, a photothermometer 126. .

[0105] After 118 hours of diamond growth, the diamond growth reaction was stopped and the silicon substrate 4 A diamond film 6 having a thickness of 190 μm was deposited conformally on the surface 12 of the The silicon-diamond composite substrate was obtained. The diamond growth surface was a diamond film. While the diamond film 6 is attached to the silicon substrate 4, it is optically finished and the thickness (diamond film 6) was polished to 140 microns.

[0106] Next, the silicon substrate 4 is removed from the silicon-diamond composite substrate (KOH aqueous solution The diamond film was then dissolved using a fluorine-based solvent (HF) to leave a free-standing diamond film 6. The nucleation surface of the doped film 6 has an average surface roughness (Ra) between 2 and 3 nm and a nucleation density of 1. 0 9 / cm 2 Above, it was a smooth surface finish. The latter two of these are, for example, It is well suited for applications such as thermal management, optical management, semiconductor devices, and friction control.

[0107] This free-standing diamond film 6 is placed 34 mm away from the scattered light collecting lens. It is characterized by a scattering coefficient of 2.09 / cm and a light scattering wavelength of 1.06 μm. It was.

[0108] Under the same diamond growth conditions, on a different silicon substrate 4, the same In several additional experiments conducted according to the pointer, problems occurred. In one example, the diamond film 6 was peeled off from the silicon substrate 4, and further polishing could not be performed on the growth surface of the peeled diamond film. These examples suggest that the process relying solely on nanodiamond seeding is not a reliable process for manufacturing a thin diamond substrate having at least one optically finished surface. This implies that the diamond film 6 does not adhere strongly to the silicon substrate 4 in the nanodiamond seeding process.

[0109] In one embodiment, as a potential aid for the adhesion of the diamond film 6 onto the substrate via the dielectric film 13, the dielectric film 13 may be included on the surface 12 of any one or more of the substrates described herein. However, this should not be construed in a limiting sense.

[0110] As disclosed herein, the laminated composite substrate includes a silicon layer having an optically finished surface and a diamond layer grown by chemical vapor deposition (CVD) on the optically finished surface of the silicon layer. At the interface between the silicon layer and the diamond layer, the optically finished surface of the silicon layer has a surface roughness (Ra) of 100 nm or less.

[0111] The laminated composite substrate may optionally include a dielectric layer or film between the silicon layer and the diamond layer. The dielectric layer can be SiO or SiN. 2

[0112] At the interface between the silicon layer and the diamond layer, the optically finished surface of the silicon layer The surface can have an Ra of 1 nm or less.

[0113] At the interface between the silicon layer and the diamond layer, the surface of the diamond layer can have an Ra greater than that of the optically finished surface of the silicon layer.

[0114] At the interface between the silicon layer and the diamond layer, the particle density of diamond can be 10 9 d iamond particles / cm 2 or more, or 10 4 diamond particles / cm 2 or more.

[0115] The silicon layer can have a thickness of 5000 μm or more, or a thickness of 10 μm or more.

[0116] The diamond layer can have a thickness of 2000 μm or less, or a thickness of 5 μm or less.

[0117] The laminated substrate can have a maximum dimension of 25.4 mm or more, or a maximum dimension of 152.4 mm or more.

[0118] The laminated substrate can have a total thickness of the silicon layer and the diamond layer of 50 μm or more, or a total thickness of the silicon layer and the diamond layer of 5 mm or more.

[0119] The surface of the diamond layer on the side opposite to the silicon layer can have an Ra of 100 nm or less, or an Ra of 5 nm or less.

[0120] The light management coating can be included on the surface of the diamond layer on the side opposite to the silicon layer.

[0121] The diamond crystals on the surface of the diamond layer opposite to the silicon layer are 13 between 31.9 and 1332.1 cm -1 have a Raman peak, and between 2.8 and 6.2 cm -1 of have the full width at half maximum (FWMH) of the Raman spectrum, or have both of them, which is possible.

[0122] Furthermore, (a) providing a silicon layer having the optically finished surface; (b) after the step (a), seeding diamond powder on the optically finished surface of the silicon layer; (c) after the step (b), CVD depositing a diamond layer on the diamond seeded on the optically finished surface of the silicon layer; ( d) continuing the step of CVD depositing the diamond layer on the diamond seeded on the optically finished surface of the silicon layer until the diamond layer of a predetermined thickness is deposited on the diamond seeded on the optically finished surface of the silicon layer, is disclosed, a method for forming the laminated substrate of claim 1. The method may include, between the steps (c) and (d), (c1) stopping the step of CVD depositing the diamond layer on the diamond seeded on the optically finished surface of the silicon layer; (c2) seeding diamond powder on the optically finished surface of the silicon layer including the CVD-deposited diamond layer of the step (c).

[0123] The silicon layer in the step (a) is the surface of the silicon layer opposite to the optically finished surface.

[0124] (a) The silicon layer in the step is the surface of the silicon layer opposite to the optically finished surface. ​​​​​​​​can include a substrate bonded thereto. The substrate can be made thicker than the silicon layer. can be.

[0125] The method can further include (e) polishing the surface of the diamond layer on the side opposite to the silicon layer for optical finishing. can be.

[0126] The method can further include applying an optical management coating to the polished surface of the diamond layer on the side opposite to the silicon layer. can be.

[0127] The above embodiments have been described with respect to a laminated composite substrate including a silicon layer having a chemical vapor deposition (CVD) grown diamond layer deposited on the surface of the silicon layer, but the laminated composite substrate according to the guidelines described herein can also be assumed to include CVD growth of a diamond layer on the surface of any suitable and / or desirable lattice-matched substrate. can be. According to the guidelines described herein, a laminated composite substrate can also be assumed to include CVD growth of a diamond layer on the surface of any suitable and / or desirable lattice-matched substrate. can be.

[0128] In one embodiment, diamond has a lattice constant of 3.57 angstroms at 300K, and silicon has a lattice constant of 5.43 angstroms. The lattice constants of other components at 300K are known in the art and are not described herein for simplicity. In one embodiment, diamond has a lattice constant of 3.57 angstroms at 300K, and silicon has a lattice constant of 5.43 angstroms. The lattice constants of other components at 300K are known in the art and are not described herein for simplicity. The lattice constants of other components at 300K are known in the art and are not described herein for simplicity.

[0129] In one embodiment, the diamond layer 6 can be grown on a substrate made of any suitable and / or desirable material or combination of materials. The substrate can be crystalline or amorphous (non-crystalline) material. In one embodiment, when the substrate is made of a crystalline material, the complete lattice mismatch between the diamond layer 6 and the substrate, i.e., the difference between the lattice constant of the diamond layer and the lattice constant of the substrate, can be 0 to 4.5 angstroms. Here, "lattice one" In one embodiment, the diamond layer 6 can be grown on a substrate made of any suitable and / or desirable material or combination of materials. The substrate can be crystalline or amorphous (non-crystalline) material. In one embodiment, when the substrate is made of a crystalline material, the complete lattice mismatch between the diamond layer 6 and the substrate, i.e., the difference between the lattice constant of the diamond layer and the lattice constant of the substrate, can be 0 to 4.5 angstroms. Here, "lattice one" In one embodiment, the diamond layer 6 can be grown on a substrate made of any suitable and / or desirable material or combination of materials. The substrate can be crystalline or amorphous (non-crystalline) material. In one embodiment, when the substrate is made of a crystalline material, the complete lattice mismatch between the diamond layer 6 and the substrate, i.e., the difference between the lattice constant of the diamond layer and the lattice constant of the substrate, can be 0 to 4.5 angstroms. Here, "lattice one" In one embodiment, when the substrate is made of a crystalline material, the complete lattice mismatch between the diamond layer 6 and the substrate, i.e., the difference between the lattice constant of the diamond layer and the lattice constant of the substrate, can be 0 to 4.5 angstroms. Here, "lattice one" In one embodiment, when the substrate is made of a crystalline material, the complete lattice mismatch between the diamond layer 6 and the substrate, i.e., the difference between the lattice constant of the diamond layer and the lattice constant of the substrate, can be 0 to 4.5 angstroms. Here, "lattice one" "To the substrate" means a complete lattice mismatch between the substrate (of any material) and the diamond layer 6, i.e., the difference between the lattice constant of the diamond layer and the lattice constant of the substrate is between 0 and 4. 5 angstroms, for example, 4.5 angstroms or less, 3.5 angstroms or less, 2.5 angstroms or less, or 2.0 angstroms or less. The diamond layer 6 can be successfully CVD grown on the surface of one or more lattice-matched substrates known in the art in accordance with the guidelines described herein.

[0130] The above embodiments have been described with reference to the accompanying drawings. Provided for the purpose of explanation, the above embodiments should not be construed in a limiting sense. Upon reading and understanding the above embodiments, design changes and partial changes can also be made to other things. Therefore, the above embodiments should not be construed as a limiting disclosure.

Claims

1. A silicon layer having a surface with a surface roughness (Ra) of 100 nm or less and having an optically finished surface, A diamond layer on the optically finished surface, the diamond layer grown by chemical vapor deposition (CVD), and comprising: The diamond layer has a 1.064 micron light scattering coefficient of 7 / cm or less, the light scattering coefficient being measured using a Nd-YAG solid 1.064 micron wavelength laser, and is determined by the ratio of the scattered light intensity collected at a distance of 34 cm from the shielding lens to the total light intensity including the transmitted light, The optically finished surface of the diamond layer that adheres to the optically finished surface of the silicon layer has a surface roughness (Ra) of 100 nm or less, A laminated substrate.

2. The laminated substrate according to claim 1, wherein the diamond layer has a 1.064 micron light scattering coefficient of 5 / cm or less at a distance of 34 cm from the shielding lens.

3. The diamond layer has a diamond nucleation density of 1.0×10 ５ / cm ２ or more, and the laminated substrate according to claim 1.

4. The diamond layer has a diamond nucleation density of 1.0×10 ９ / cm ２ or more, and the laminated substrate according to claim 1.

5. The laminated substrate according to claim 1, wherein the silicon layer includes a dielectric film.

6. The laminated substrate according to claim 1, further comprising one or more light management coatings disposed on the exposed surface of the laminated substrate.

7. The laminated substrate according to claim 6, wherein the exposed surface is a surface of the diamond layer disposed on the side opposite to the silicon layer.

8. The laminated substrate according to claim 1, wherein the surface of the silicon layer opposite to the diamond layer is bonded to another substrate.

9. The laminated substrate according to claim 8, wherein the another substrate is made of any one of silicon, graphite, metal, ceramic, or glass.

10. The laminated substrate according to claim 1, wherein the silicon layer includes an n-type dopant or a p-type dopant.

11. The laminated substrate according to claim 1, wherein the diamond layer includes an n-type dopant or a p-type dopant.

12. Comprising a first substrate and a second substrate bonded to the first substrate, The second substrate is formed of at least silicon, has an optically finished surface on the opposite side of the first substrate, and the optically finished surface has a surface roughness (Ra) of 100 nm or less, Furthermore, a diamond layer grown by chemical vapor deposition (CVD) is provided on the optically finished surface of the second substrate. The diamond layer has a 1.064 micron light scattering coefficient of 7 / cm or less, which is measured using a Nd-YAG solid 1.064 micron wavelength laser and is determined by the ratio of the scattered light intensity collected at a distance of 34 cm from the shielding lens to the total light intensity including transmitted light. The optically finished surface of the diamond layer that adheres to the optically finished surface of the second substrate has a surface roughness (Ra) of 100 nm or less. Laminated substrate.

13. The first substrate is made of any one of silicon, graphite, metal, ceramic, or glass. The laminated substrate according to claim 12.

14. The second substrate is bonded to the first substrate by a bonding reagent. The bonding reagent includes at least one of a polymer, a silicate material, and a metal material. The laminated substrate according to claim 12.

15. A silicon layer having a surface roughness (Ra) of 100 nm or less and an optically finished surface, A diamond layer on the optically finished surface, which is a diamond layer grown by chemical vapor deposition (CVD). At least one of the silicon layer and the diamond layer contains an n-type dopant or a p-type dopant. The diamond layer has a 1.064 micron light scattering coefficient of 7 / cm or less, which is measured using a Nd-YAG solid 1.064 micron wavelength laser and is determined by the ratio of the scattered light intensity collected at a distance of 34 cm from the shielding lens to the total light intensity including transmitted light. The optically finished surface of the diamond layer that adheres to the optically finished surface of the silicon layer has a surface roughness (Ra) of 100 nm or less. Laminated substrate.

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