A process for semiconductor modification of diamond tool material

Abstract

The invention relates to the technical field of diamond synthesis, and in particular to a process for semiconductor modification of diamond tool materials. A carbon source, a modified catalyst, a seed crystal and a crystal bed are arranged in sequence from the high-temperature end to the low-temperature end of a cavity, and a high-temperature and high-pressure temperature gradient method is adopted to perform boron-hydrogen synergistic doping to synthesize a diamond single crystal. The carbon source is high-purity graphite powder, and the modified catalyst is formed by mixing LiAIH4 powder, amorphous boron powder, high-purity titanium powder and FeNiCo alloy catalyst; the LiAIH4 is used as a doped hydrogen source, and the doping mass ratio is 0.02wt.%-0.05wt.% of the carbon source; the high-purity amorphous boron powder is used as a doped boron source, and the doping mass ratio is 0.5wt.%-2.0wt.% of the carbon source; the high-purity titanium powder is used as a denitrifier, and the doping mass ratio is 0.7wt.%-1.0wt.% of the modified catalyst. The present application adds amorphous boron powder as a boron source for diamond semiconductor modification, high-purity Ti powder as a denitrifier to increase the boron doping rate inside the diamond, and LiAIH4 as a hydrogen source, thereby effectively improving the carrier transport capacity inside the boron-doped diamond.

Description

Technical Field

[0001] The invention relates to the technical field of diamond synthesis, and in particular to a process for realizing semiconductor modification of diamond tool materials through boron-hydrogen synergistic doping. Background Art

[0002] Single crystal diamond is widely used in single-point diamond ultra-precision turning tools due to its extremely high hardness, wear resistance and thermal conductivity, extremely low friction coefficient, thermal expansion coefficient and chemical activity, and excellent grinding performance. With the development of diamond artificial synthesis technology, artificial diamonds with large size, stable quality, adjustable growth process and relatively low cost are being used in an increasing proportion of ultra-precision machining tools.

[0003] Cutting temperature has a great influence on the cutting process. It will change the contact state between the tool and the workpiece, interfere with the size and shape accuracy of the machined surface, and increase tool wear. Therefore, the cutting temperature needs to be monitored online. If the diamond tool body has temperature-sensing material properties, the temperature measurement of the quasi-cutting area can be achieved without the need for an external sensor, which has a subversive significance for the improvement of online cutting temperature measurement technology.

[0004] Diamond has high electron mobility and a wide bandgap, and is theoretically feasible for semiconductor modification. The modified diamond has the inherent thermal sensitivity of semiconductor materials and can be used as a temperature sensor. The extremely short covalent bonds of carbon atoms in diamond limit the doping of many atoms in space. Among the many impurity elements, the diameter of boron atoms is slightly smaller than that of carbon atoms, and it is relatively easy to enter the diamond lattice. In addition, it has 3 outer electrons, which can introduce shallow impurity energy levels in the diamond bandgap to make it have P-type semiconductor properties. Therefore, this plan plans to use boron as the main doping source for diamond semiconductor modification. Summary of the invention

[0005] The purpose of the present invention is to provide a process for achieving semiconductor modification of diamond tool materials through boron-hydrogen co-doping.

[0006] The purpose of the invention is achieved in this way:

[0007] A process for semiconductor modification of diamond tool materials, wherein a carbon source, a modified catalyst, a seed crystal and a crystal bed are arranged in sequence from the high temperature end to the low temperature end of a cavity, and a high temperature and high pressure temperature gradient method is used to perform boron-hydrogen synergistic doping to synthesize diamond single crystals.

[0008] The carbon source is high-purity graphite powder,

[0009] The modified catalyst is a mixture of LiAIH4 powder, amorphous boron powder, high-purity titanium powder and FeNiCo alloy catalyst;

[0010] The LiAIH4 is used as a doped hydrogen source, and the doping mass ratio is 0.02wt.%-0.05wt.% of the carbon source.

[0011] The high-purity amorphous boron powder is used as a doped boron source, and the doping mass ratio is 0.5wt.%-2.0wt.% of the carbon source;

[0012] The high-purity titanium powder is used as a denitrifier, and the doping mass ratio of the modified catalyst is 0.7wt.%-1.0wt.%.

[0013] Preferably, the doping mass ratio of the FeNiCo alloy catalyst is Fe:Ni:Co=65:30:5.

[0014] Preferably, the LiAIH4 doping mass ratio is 0.03wt.% of the carbon source; the high-purity amorphous boron powder doping mass ratio is 1.0wt.% of the carbon source; and the high-purity titanium powder doping mass ratio is 0.9wt.% of the modified catalyst.

[0015] Preferably, the internal pressure of the cavity is 5.0-5.5 GPa, and the internal center temperature of the cavity is 1400-1500°C.

[0016] Preferably, when preparing the modified catalyst, amorphous boron powder, LiAIH4 powder and high-purity titanium powder with different mass fractions are mixed into FeNiCo alloy catalyst as needed.

[0017] Preferably, the cavity comprises

[0018] A magnesium oxide cup, located in the inner layer and capable of accommodating the carbon source, modified catalyst, seed crystal and crystal bed;

[0019] A graphite heating tube is arranged around the outside of the magnesium oxide cup;

[0020] Dolomite is arranged around the graphite heating tube;

[0021] The pyrophyllite is arranged around the dolomite to form the outer layer of the cavity.

[0022] Preferably, steel caps are provided on both sides of the high-temperature end and the low-temperature end of the cavity, and the steel caps are located outside the dolomite.

[0023] Preferably, an alumina gasket is provided between the carbon source and the inner wall of the magnesium oxide cup on one side of the high temperature end.

[0024] Compared with the prior art, the present invention has the following outstanding and beneficial technical effects:

[0025] Compared with the prior art, the diamond synthesis process of the present invention greatly improves the boron doping rate inside the diamond through nitrogen removal treatment, and effectively improves the carrier transport capacity inside the material through boron-hydrogen synergistic doping, thereby ensuring that the material has excellent sharpening and cutting properties as a tool, and also has material performance conditions as a temperature sensor. In terms of material synthesis process, the diamond single crystal synthesized by the process method has excellent quality, regular and symmetrical shape, simple process operation, low cost, repeatability, and can meet the requirements of mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the assembly of boron-hydrogen co-doped nitrogen-removed diamond single crystals synthesized by high temperature and high pressure temperature gradient method.

[0027] Figure 2 This is a photo of the boron hydride co-doped diamond single crystal sample after acid pickling and polishing.

[0028] Figure 3 These are the Raman spectra results of boron-hydrogen co-doped diamond 100 and 111 crystal planes.

[0029] Figure 4 These are the infrared spectra results of boron-hydrogen co-doped diamond 100 and 111 crystal planes.

[0030] Figure 5 These are the calibration results of the thermal sensitive properties of boron-hydrogen co-doped diamond.

[0031] Figure 6 This is a photo of a diamond-ground ultra-precision machining tool.

[0032] Figure 7 This is the measurement result of the cutting edge radius of the diamond tool after sharpening under AFM. DETAILED DESCRIPTION

[0033] The following are specific embodiments of the present invention, and the technical solutions of the present invention are further described in conjunction with the accompanying drawings, but the present invention is not limited to these embodiments.

[0034] A process for semiconductor modification of diamond tool materials, wherein a carbon source 7, a modified catalyst 8, a seed crystal 9 and a crystal bed 10 are arranged in sequence from the high temperature end to the low temperature end of a cavity, and a high temperature and high pressure temperature gradient method is used to perform boron-hydrogen synergistic doping to synthesize a diamond single crystal.

[0035] The carbon source is high-purity graphite powder; when preparing the modified catalyst, different mass fractions of amorphous boron powder, LiAIH4 powder, and high-purity titanium powder are mixed in the FeNiCo alloy catalyst as needed. If only FeNiCo alloy is used as a synthetic catalyst, the synthesized diamond is an insulator; on the basis of FeNiCo alloy, LiAIH4 powder, amorphous boron powder, and high-purity titanium powder are added; the LiAIH4 is used as a doped hydrogen source, and the doping mass ratio is 0.02wt.%-0.05wt.% of the carbon source; the high-purity amorphous boron powder is used as a doped boron source, and the doping mass ratio is 0.5wt.%-2.0wt.% of the carbon source; the high-purity titanium powder is used as a denitrifier, and the doping mass ratio is 0.7wt.%-1.0wt.% of the modified catalyst.

[0036] The purity of high-purity titanium powder and high-purity graphite powder are both required to reach 99.99wt.%.

[0037] Preferably, the doping mass ratio of the FeNiCo alloy catalyst is Fe:Ni:Co=65:30:5.

[0038] Preferably, the LiAIH4 doping mass ratio is 0.03wt.% of the carbon source; the high-purity amorphous boron powder doping mass ratio is 1.0wt.% of the carbon source; and the high-purity titanium powder doping mass ratio is 0.9wt.% of the modified catalyst.

[0039] Preferably, the internal pressure of the cavity is 5.0-5.5 GPa, and the internal center temperature of the cavity is 1400-1500° C. In this embodiment, the internal center temperature of the cavity is 1440° C.

[0040] Diamonds are synthesized in a domestic hinged six-sided top-pressing device. In order to achieve the crystal size required for diamond tools, the diamond synthesis time is 46 hours. After diamond synthesis, it needs to be pickled and polished.

[0041] The hinged six-sided pressing device has a cavity, which includes

[0042] The magnesium oxide cup 4 is located in the inner layer and can accommodate the carbon source 7, the modified catalyst 8, the seed crystal 9 and the crystal bed 10;

[0043] A graphite heating tube 3 is arranged around the outside of the magnesium oxide cup 4;

[0044] Dolomite 2, arranged around the graphite heating tube 3;

[0045] The pyrophyllite 1 is arranged around the dolomite 2 to form the outer layer of the cavity.

[0046] Preferably, steel caps 5 are provided on both sides of the high temperature end and the low temperature end of the cavity, and the steel caps 5 are located outside the dolomite 2. The magnesium oxide cup, dolomite and pyrophyllite are for heat preservation and pressure maintenance, and the steel caps are for electrical conductivity.

[0047] Preferably, an alumina gasket 6 is provided between the carbon source 7 and the inner wall of the magnesium oxide cup 4 at the high temperature end, for heat transfer and electrical isolation between the heat generating component and the carbon source.

[0048] The synthesized boron-hydrogen co-doped diamond single crystal material was subjected to component testing, grinding property testing, and thermal property testing. The component testing was to evaluate the boron doping situation, and the grinding property testing was to evaluate whether the boron-hydrogen co-doped diamond single crystal could be ground to the cutting edge radius required for ultra-precision machining. The thermal property testing was to evaluate whether the material could be used as a temperature-sensitive material.

[0049] The boron-hydrogen co-doped diamond single crystal synthesized by the process method is as follows: Figure 2 As shown, the crystal geometric size is about 4mm×4mm×1mm, with a regular shape and good symmetry.

[0050] Raman spectroscopy was performed on the samples ( Figure 3 ) and infrared spectroscopy ( Figure 4 ) test, the results show that the boron characteristic peaks on the 100 and 111 crystal planes of diamond are obvious. The greater the intensity of the diffraction peak, the better the degree of crystallization, the larger the grains, and the orderly growth of the corresponding crystal planes.

[0051] The samples were tested for thermal sensitivity, and the results were as follows: Figure 5 As shown, the test results show that boron hydride co-doped diamond material has significant negative temperature coefficient thermal sensitivity in the temperature range of 298K-398K.

[0052] The samples were sharpened into ultra-precision machining tools ( Figure 6 ), the tool edge radius after testing and grinding is about 35nm ( Figure 7 ), good sharpening properties.

[0053] The diamond material synthesized by the scheme passed component testing, sharpening property testing, and thermal sensitivity testing, and it was finally determined that it can be used as a temperature-sensitive diamond tool material.

[0054] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for semiconductor modification of diamond tool material, wherein a carbon source (7), a modified catalyst (8), a seed crystal (9) and a crystal bed (10) are arranged in sequence from the high temperature end to the low temperature end of a cavity, and a high temperature and high pressure temperature gradient method is used to perform boron-hydrogen co-doping to synthesize a diamond single crystal, characterized in that: The carbon source is high-purity graphite powder, The modified catalyst is a mixture of LiAIH4 powder, high-purity amorphous boron powder, high-purity titanium powder and FeNiCo alloy catalyst; The LiAIH4 is used as a doped hydrogen source, and the doping mass ratio is 0.02wt.%-0.05wt.% of the carbon source. The high-purity amorphous boron powder is used as a doped boron source, and the doping mass ratio is 0.5wt.%-2.0wt.% of the carbon source; The high-purity titanium powder is used as a denitrifying agent, and the doping mass ratio of the modified catalyst is 0.7wt.%-1.0wt.%.

2. The process for semiconductor modification of diamond tool material according to claim 1, characterized in that: The doping mass ratio of the FeNiCo alloy catalyst is Fe:Ni:Co=65:30:

5.

3. The process for semiconductor modification of diamond tool material according to claim 1, characterized in that: The doping mass ratio of LiAIH4 is 0.03wt.% of the carbon source; the doping mass ratio of the high-purity amorphous boron powder is 1.0wt.% of the carbon source; and the doping mass ratio of the high-purity titanium powder is 0.9wt.% of the modified catalyst.

4. The process for semiconductor modification of diamond tool material according to claim 1, characterized in that: The internal pressure of the cavity is 5.0-5.5 GPa, and the central temperature of the cavity is 1400-1500°C.

5. The process for semiconductor modification of diamond tool material according to claim 1, characterized in that: When preparing the modified catalyst, high-purity amorphous boron powder, LiAIH4 powder and high-purity titanium powder with different mass fractions are mixed into the FeNiCo alloy catalyst as required.

6. The process for semiconductor modification of diamond tool material according to claim 1, characterized in that: The cavity includes A magnesium oxide cup (4), located in the inner layer and capable of accommodating the carbon source (7), the modified catalyst (8), the seed crystal (9) and the crystal bed (10); A graphite heating tube (3) is arranged around the outside of the magnesium oxide cup (4); Dolomite (2) is arranged around the graphite heating tube (3); The pyrophyllite (1) is arranged around the dolomite (2) to form an outer layer of the cavity.

7. The process for semiconductor modification of diamond tool material according to claim 6, characterized in that: Steel caps (5) are provided on both sides of the high-temperature end and the low-temperature end of the cavity, and the steel caps (5) are located outside the dolomite (2).

8. The process for semiconductor modification of diamond tool material according to claim 5, characterized in that: An alumina gasket (6) is provided between the carbon source (7) and the inner wall of the magnesium oxide cup (4) on the high-temperature end side.

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