Monocrystalline silicon dopant and preparation method and application thereof
By using MOFs-5 and graphene quantum dots as dopants in single-crystal silicon, combined with pulsed laser technology, the problems of uniformity and thermal damage in the single-crystal silicon doping process were solved, achieving low-temperature and high-efficiency doping effects to meet the needs of high-end semiconductor devices.
Patent Information
- Application Number
- CN202511119460.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-11
- Publication Date
- 2025-11-18
AI Technical Summary
Existing single-crystal silicon doping processes suffer from drawbacks such as poor doping uniformity, the need for high-temperature processing, high cost, and thermal damage to silicon wafers, making it difficult to meet the demands of high-end semiconductor devices.
Using MOFs-5 as the dopant element carrier, combined with graphene quantum dots and starch-based binders, a novel single-crystal silicon dopant was prepared by pulsed laser-induced doping technology, achieving uniform distribution and controllable release of dopant elements, and reducing the processing temperature to below 300℃.
This method achieves efficient and uniform doping of monocrystalline silicon wafers, avoids thermal damage to silicon wafers caused by high-temperature doping, improves doping accuracy and uniformity, and reduces energy consumption and cost.
Smart Images
Figure BDA0005542447280000091
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of semiconductor, in particular to a single crystal silicon dopant and a preparation method and application thereof. BACKGROUND
[0002] As a basic material of semiconductor industry, the doping process of single crystal silicon wafer directly affects the key electrical properties of semiconductor devices such as carrier concentration, mobility and breakdown voltage. The traditional doping method has problems such as poor doping uniformity, high diffusion temperature, high energy consumption, etc., which leads to unstable electrical properties of single crystal silicon wafer and is difficult to meet the needs of high-end semiconductor devices. For example, in the high-temperature diffusion process of thermal diffusion doping method, the diffusion coefficient of doping atoms such as B, P and As in the silicon lattice is affected by temperature gradient, crystal orientation and surface oxide layer, which easily leads to non-uniform radial or axial concentration gradient; at the same time, high temperature above 1000℃ will cause thermal defects of vacancies or interstitial atoms in silicon lattice, which will cause carrier scattering to increase and mobility to decrease. For another example, after ion implantation and high-temperature annealing, high-energy ion implantation will cause collision damage in the silicon lattice, which needs to be repaired by annealing at a temperature above 1000℃, and for the same reason, the above-mentioned high-temperature defects exist, in addition, the point defects of interstitial silicon atoms at high temperature will accelerate the diffusion of doping atoms, leading to uncontrollable junction depth.
[0003] In addition to the defects in the doping process, the existing or common dopants often cannot accurately control the distribution and concentration of the doping elements during use, and will cause a certain degree of thermal damage to the silicon wafer during the doping process. In addition, the preparation process of some dopants is complex and the cost is high, which is not conducive to large-scale production. Therefore, it is of great practical significance to develop a dopant which is efficient, uniform and can realize low-temperature doping and a preparation method thereof.
[0004] Therefore, the present application is proposed. SUMMARY
[0005] The first object of the present application is to provide a single crystal silicon dopant to solve the defects of the existing dopants such as poor doping uniformity, high-temperature treatment, high cost and thermal damage to silicon wafer, and to realize the advantages of high efficiency, uniformity and low temperature in the doping process of single crystal silicon.
[0006] The second object of the present application is to provide a preparation method of the single crystal silicon dopant.
[0007] The third object of the present application is to provide a preparation method of single crystal silicon, which can effectively solve the damage to the silicon wafer caused by the conventional high-temperature doping environment.
[0008] The fourth object of the present application is to provide the use of the single crystal silicon dopant in the field of semiconductors.
[0009] In order to achieve the above-mentioned object of the present application, the following technical solutions are adopted:
[0010] A single crystal silicon dopant, comprising the following ingredients by weight fraction:
[0011] MOFs-5 6-10 parts, tri-tert-butyl phosphine 3-5 parts, graphene quantum dots 1-5 parts, starch-based binder 0.5-1 parts, ionic liquid 4-5 parts, boric acid 5-10 parts, ammonium dihydrogen phosphate 3-7 parts, polyethylene glycol 5-8 parts, and a solvent;
[0012] The starch-based binder comprises the following ingredients by mass percentage: esterified starch 40-60%, nano-silicon dioxide 10-20%, montmorillonite 20-30%, and calcium carbonate 5-15%.
[0013] A preparation method of the single crystal silicon dopant, comprising the following steps:
[0014] Mixing MOFs-5, tri-tert-butyl phosphine, graphene quantum dots, a starch-based binder, an ionic liquid, boric acid, ammonium dihydrogen phosphate, polyethylene glycol, and a solvent uniformly to obtain the single crystal silicon dopant.
[0015] A preparation method of single crystal silicon, which adopts the single crystal silicon dopant; and the preparation method is performed by pulsed laser.
[0016] And the use of the single crystal silicon dopant in semiconductors.
[0017] Compared with the prior art, the present application has the following beneficial effects:
[0018] The present application provides a new type of single crystal silicon dopant, which uses MOFs-5 as a carrier of doping elements, has a high specific surface area and a porous structure, can load a large amount of doping elements, and can realize uniform distribution and controlled release of the doping elements; at the same time, the present application introduces graphene quantum dots as a laser absorption enhancer, greatly improves the photo-thermal conversion efficiency, makes the laser-induced doping process more efficient, and reduces the thermal damage to the single crystal silicon wafer.
[0019] When the dopant of the present application is used for single crystal silicon doping, the pulsed laser-induced doping technology can realize ultrafast doping (processing time <1s) and low-temperature processing (surface temperature ≤300℃), avoid the thermal damage to the single crystal silicon wafer caused by traditional high-temperature doping, and improve the precision and uniformity of doping. DETAILED DESCRIPTION
[0020] The technical solutions of the present application will be described clearly and completely in combination with the specific embodiments below, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, rather than all the embodiments, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market. In addition, the terms "first", "second", "third" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance.
[0021] The first aspect of the present application is to provide a single crystal silicon dopant, which is mainly prepared from the following components by weight parts: MOFs-5 6-10 parts, tri-tert-butyl phosphine 3-5 parts, graphene quantum dots 1-5 parts, starch-based binder 0.5-1 parts, ionic liquid 4-5 parts, boric acid 5-10 parts, ammonium dihydrogen phosphate 3-7 parts, polyethylene glycol 5-8 parts, and solvent; wherein the starch-based binder comprises the following components by mass percentage: esterified starch 40%-60%, nano-silicon dioxide 10%-20%, montmorillonite 20%-30%, and calcium carbonate 5%-15%.
[0022] In the present application, a specific MOFs material "MOFs-5" is provided, which mainly provides the following technical effects when used as a component of a single crystal silicon dopant: as a platform for uniformly loading doping elements, achieving slow release of the dopant through channel confinement effect in the doping process, avoiding aggregation of doping elements, etc.
[0023] As a preferred embodiment, the monomer particle size of the MOFs-5 is 200 μm ± 60 μm, the specific surface area of the MOFs-5 is 1000 m 2 / g-3000 m 2 / g, and the average pore size of the channels of the MOFs-5 is 0.8 nm-1.8 nm.
[0024] As a preferred embodiment, the MOFs-5 is prepared from terephthalic acid and a soluble zinc salt.
[0025] In the present application, the MOFs-5 can be purchased through market channels, but in some cases it is difficult to directly purchase the MOFs-5 that meets the characteristics defined in the above preferred embodiments, or the quality of the purchased MOFs-5 is unstable. Therefore, the present application provides a method for self-preparing the MOFs-5.
[0026] As an optional embodiment, the preparation method of the MOFs-5 comprises the following steps: dissolving the terephthalic acid and the soluble zinc salt in an organic solvent to obtain a solution with a concentration of 0.05 mol / L-0.3 mol / L; placing the solution in 110℃-140℃ for 20h-30h, and then separating the solid phase to obtain the MOFs-5 after washing and drying. Further, in some embodiments, the molar ratio of the terephthalic acid to the soluble zinc salt is 1:(1-1.2).
[0027] The graphene quantum dots used in the present application are a kind of zero-dimensional carbon nanomaterials, which are nanoparticles formed by size limitation and edge modification of single-layer or few-layer graphene, and have advantages of good optical performance, chemical stability, biocompatibility, edge structure diversity, conductivity and electrochemical activity, etc.
[0028] As a preferred embodiment, the molecular weight of the graphene quantum dots is ≤1000 Da.
[0029] As an optional embodiment, the preparation method of the graphene quantum dots comprises the following steps: S1, adding graphite powder into concentrated sulfuric acid and concentrated nitric acid and performing ice bath treatment; S2, adding potassium permanganate into the mixture of S1 and fully mixing and reacting; S3, heating the mixture of S2 to 35℃ and fully mixing and reacting; S4, adding water into the mixture of S3 and fully mixing; S5, adding hydrogen peroxide into the mixture of S4 until the color of the mixture turns bright yellow; S6, separating the mixture of S5 and obtaining the supernatant, performing dialysis treatment and evaporating and concentrating to obtain the graphene quantum dots.
[0030] As a preferred embodiment, the ionic liquid comprises at least one of imidazole ionic liquid or quaternary ammonium salt ionic liquid; in some optional embodiments, the imidazole ionic liquid comprises but is not limited to 1-butyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium bis-trifluoromethanesulfonimide, 1-octyl-3-methylimidazolium chloride, etc., and the quaternary ammonium salt ionic liquid comprises but is not limited to tetrabutylammonium chloride, trimethylhexadecylammonium bis-trifluoromethanesulfonimide, tetraethylammonium tetrafluoroborate, N-butyl-N-methylpyrrolidinium bis-trifluoromethanesulfonimide, etc.
[0031] As a preferred embodiment, the average molecular weight of the polyethylene glycol is 200-600, and more preferably, PEG-400 is used.
[0032] As a preferred embodiment, the solvent comprises a combination of terpineol and deionized water, and the oil-water mass ratio of the solvent is 0.35-0.45:0.55-0.65.
[0033] In the present application, the above solvent combination is preferred, wherein, terpineol is an organic solvent with high boiling point (214℃), which can delay the drying speed of the dopant and avoid film cracking; deionized water can adjust the solution polarity and promote the dissolution of other components (such as ionic liquid and starch-based binder); further, by coordinating the ratio of the two, the balance of the evaporation rate and the film uniformity can be controlled.
[0034] As a preferred embodiment, the single crystal silicon dopant is prepared by mixing the following components in percentage by weight: MOFs-5 6%~10%, tri-tert-butyl phosphine 3%~5%, graphene quantum dots 1%~5%, starch-based binder 0.5%~1%, ionic liquid 4%~5%, boric acid 5%~10%, ammonium dihydrogen phosphate 3%~7%, polyethylene glycol 5%~8%, and the rest is solvent.
[0035] The second aspect of the present application is to provide a preparation method of the single crystal silicon dopant as described in the first aspect, mainly comprising the following steps: mixing MOFs-5, tri-tert-butyl phosphine, graphene quantum dots, starch-based binder, ionic liquid, boric acid, ammonium dihydrogen phosphate, polyethylene glycol and solvent uniformly to obtain the single crystal silicon dopant.
[0036] As an optional embodiment, the sufficient mixing can be assisted by oscillation, stirring, shaking table, centrifugation, ultrasonic, heating and the like, which helps to accelerate the dispersion and obtain a relatively uniform dispersion system.
[0037] As a preferred embodiment, the sufficient mixing is carried out by heating and stirring, the heating temperature is 35℃~50℃, the stirring frequency is 200rpm~800rpm, and the duration of the heating and the stirring is 100min~180min.
[0038] As a preferred embodiment, the sufficient mixing is carried out by heating and stirring, the heating temperature is 35℃~50℃, the stirring frequency is 200rpm~800rpm, and the duration of the heating and the stirring is 100min~180min.
[0039] A third aspect of the present application provides a method for preparing single crystal silicon, which employs the single crystal silicon dopant as described in the first aspect, and the method is performed using a pulsed laser. Specifically, the single crystal silicon is doped with the single crystal silicon dopant by incorporating the single crystal silicon dopant in the process of preparing the single crystal silicon using the pulsed laser, thereby obtaining the single crystal silicon doped with the single crystal silicon dopant.
[0040] A fourth aspect of the present application provides the use of the single crystal silicon dopant as described in the first aspect in the field of semiconductors.
[0041] Example 1
[0042] (1) Preparation of MOFs-5: Dissolve terephthalic acid and zinc nitrate in N,N- dimethylformamide (DMF) at a molar ratio of 1:1 to prepare a solution with a total concentration of 0.1 mol / L; transfer the solution to a reaction kettle and react at 120°C for 24 h; after the reaction is completed, cool to room temperature (25°C), and separate the solid product by centrifugation, then wash with DMF and ethanol for 3 times respectively, and then vacuum dry at 80°C for 12 h to obtain MOFs-5 of the present example.
[0043] (2) Preparation of graphene quantum dots: add 1 g of graphite powder to a mixture of 10 mL of concentrated sulfuric acid and concentrated nitric acid (volume ratio of 3:1) under ice bath condition and stir for 1 h; then slowly add 0.3 g of potassium permanganate, control the reaction temperature not to exceed 20°C, and continue to stir for 2 h; then warm the reaction system to 35°C and stir for 30 min; then add 30 mL of deionized water and continue to stir for 15 min; finally add hydrogen peroxide until the reaction solution turns bright yellow, centrifuge, take the supernatant, and dialyze in a dialysis bag for 72 hours to obtain a graphene quantum dot solution; finally, concentrate it by rotary evaporation at 60°C to obtain graphene quantum dots of the present example.
[0044] (3) Prepare the following raw materials (the sum of the mass percentages of all raw materials is 100%): MOFs-5 8%, tri-tert-butylphosphine (TBP) 4%, graphene quantum dots 3%, starch-based binder (esterified starch + nano-silicon dioxide + montmorillonite + calcium carbonate, mass ratio 50:15:25:10) 0.75%, ionic liquid (Wuhan Kanos Technology Co., Ltd., 1-butyl-3-methylimidazolium dibutyl phosphate salt 663199-28-8) 4.5%, boric acid 7.5%, ammonium dihydrogen phosphate 5.5%, polyethylene glycol (PEG-400) 6.5%, and the rest is solvent (terpilenol + water, mass ratio 0.4:0.6).
[0045] (4) MOFs-5 was first added into the mixed solvent of terpineol and deionized water, and ultrasonic dispersion was performed for 30 min to obtain a uniform suspension; then, tri-tert-butyl phosphine, graphene quantum dots, starch-based binder, ionic liquid, boric acid, ammonium dihydrogen phosphate and polyethylene glycol were sequentially added, and stirring was performed at 40℃ for 2h to fully mix and uniformly disperse the components, thereby obtaining the MOFs-based laser-induced monocrystalline silicon wafer high-efficiency dopant of the example.
[0046] Example 2
[0047] The example 2 is basically the same as the example 1, except that in step (3), MOFs-5 6%, tri-tert-butyl phosphine 3%, graphene quantum dots 1%, starch-based binder 0.5%, ionic liquid 4%, boric acid 5%, ammonium dihydrogen phosphate 3%, polyethylene glycol 5%, and the balance is solvent.
[0048] Example 3
[0049] The example 3 is basically the same as the example 1, except that in step (3), MOFs-5 10%, tri-tert-butyl phosphine 5%, graphene quantum dots 5%, starch-based binder 1%, ionic liquid 5%, boric acid 10%, ammonium dihydrogen phosphate 7%, polyethylene glycol 8%, and the balance is solvent.
[0050] Example 4
[0051] The example 4 is basically the same as the example 1, except that in step (3), the starch-based binder includes esterified starch + nano-silicon dioxide + montmorillonite + calcium carbonate, and the mass ratio is 55:12:26:7.
[0052] Comparative Example 1: The comparative example 1 is basically the same as the example 1, except that the starch-based binder is replaced by a conventional binder SBR.
[0053] Comparative Example 2: The comparative example 2 is basically the same as the example 1, except that the MOFs-5 in step (1) is replaced by a conventional MOFs material ZIF-8.
[0054] Comparative Example 3: The comparative example 3 is basically the same as the example 1, except that in step (3), MOFs-5 54%, tri-tert-butyl phosphine 3%, graphene quantum dots 2%, starch-based binder 0.5%, ionic liquid 4%, boric acid 5%, ammonium dihydrogen phosphate 3%, polyethylene glycol 5%, and the balance is solvent.
[0055] Comparative Example 4: A kind of traditional commercial dopant is used.
[0056] Test Example
[0057] The modified monocrystalline silicon wafer was prepared by using the dopant corresponding to each example or comparative example, and performance test was performed, and the test items were as follows, and the test results were recorded in Table 1.
[0058] (1) Doping concentration uniformity: Referring to GB / T17359-2012, using SEM-EDS area scanning (point spacing ≤ 5 μm, acceleration voltage 15 kV, beam current 10 nA, collection time ≥ 120 s / region).
[0059] (2) Surface concentration: Referring to GB / T29732-2013, using XPS depth profiling (Ar + etching rate 0.5 nm / s, monochromatic Al Kα source (1486.6 eV), energy resolution ≤ 0.8 eV, detection area 100 μm x 100 μm), detecting the peak intensity of Ni2p3 / 2 and Mg1s, and calculating the concentration of doping elements on the surface of monocrystalline silicon per square centimeter by the sensitivity factor method.
[0060] (3) Diffusion time: Referring to GB / T15074-2014, using diffusion couple method (Ni-Fe diffusion couple), determining the element diffusion distance by electron probe (EPMA), and recording the diffusion time.
[0061] (4) Electrical property stability: Referring to GB / T3048.5-2007, using high resistance meter (precision 10 -14 Ω, test voltage 500 V, charging time 60 s, electrode spacing 10 mm) to test the resistance of the sample, aging for 1000 hours under 85°C / 85% RH environment, and recording the resistance change rate ΔR.
[0062] (5) Calculating the energy cost consumed by the doping process of each test example.
[0063] Table 1
[0064]
[0065] Although the present application has been illustrated and described with reference to specific embodiments, it should be recognized that the present application is not limited to the embodiments discussed, but is applicable to any other embodiments falling within the scope of the present application.
[0066] The above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; those skilled in the art should understand that, without departing from the spirit and scope of the present application, modifications can be made to the technical solutions described in the above embodiments, or some or all of the technical features can be replaced by equivalent technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application; therefore, this means that, within the scope of the present application, any modifications, equivalent replacements and improvements made to the above embodiments should be considered as falling within the scope of the present application.
[0067] It should be understood by those skilled in the art that, without departing from the spirit and scope of the present application, modifications can be made to the technical solutions described in the above embodiments, or some or all of the technical features can be replaced by equivalent technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application; therefore, this means that, within the scope of the present application, any modifications, equivalent replacements and improvements made to the above embodiments should be considered as falling within the scope of the present application.
[0068] It should be understood by those skilled in the art that, without departing from the spirit and scope of the present application, modifications can be made to the technical solutions described in the above embodiments, or some or all of the technical features can be replaced by equivalent technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application; therefore, this means that, within the scope of the present application, any modifications, equivalent replacements and improvements made to the above embodiments should be considered as falling within the scope of the present application.
[0069] It should be understood by those skilled in the art that, without departing from the spirit and scope of the present application, modifications can be made to the technical solutions described in the above embodiments, or some or all of the technical features can be replaced by equivalent technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application; therefore, this means that, within the scope of the present application, any modifications, equivalent replacements and improvements made to the above embodiments should be considered as falling within the scope of the present application.
[0070] It should be understood by those skilled in the art that, without departing from the spirit and scope of the present application, modifications can be made to the technical solutions described in the above embodiments, or some or all of the technical features can be replaced by equivalent technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application; therefore, this means that, within the scope of the present application, any modifications, equivalent replacements and improvements made to the above embodiments should be considered as falling within the scope of the present application.
[0071] All such alternatives and modifications which come within the scope of the present invention are included in the appended claims.
Claims
1. A single-crystal silicon dopant, characterized in that, It is prepared from the following components in parts by weight: The ingredients include 6-10 parts of MOFs-5, 3-5 parts of tri-tert-butylphosphine, 1-5 parts of graphene quantum dots, 0.5-1 part of starch-based binder, 4-5 parts of ionic liquid, 5-10 parts of boric acid, 3-7 parts of ammonium dihydrogen phosphate, 5-8 parts of polyethylene glycol, and a certain amount of solvent. The starch-based binder comprises the following components by weight percentage: 40%–60% esterified starch, 10%–20% nano-silica, 20%–30% montmorillonite, and 5%–15% calcium carbonate.
2. The single-crystal silicon dopant according to claim 1, characterized in that, The MOFs-5 has a monomer particle size of 200 μm ± 60 μm and a specific surface area of 1000 m². 2 / g~3000m 2 / g, the average pore size of the MOFs-5 is 0.8nm to 1.8nm.
3. The single-crystal silicon dopant according to claim 1, characterized in that, The preparation method of the MOFs-5 includes the following steps: Terephthalic acid and soluble zinc salt were dissolved in an organic solvent to obtain a solution with a concentration of 0.05 mol / L to 0.3 mol / L. The solution was placed in a reaction environment of 110℃~140℃ for 20h~30h, and then the solid phase was separated. After washing and drying, the MOFs-5 was obtained.
4. The single-crystal silicon dopant according to claim 1, characterized in that, The preparation method of the graphene quantum dots includes the following steps: S1. Add graphite powder to concentrated sulfuric acid and concentrated nitric acid and perform ice bath treatment; S2. Add potassium permanganate to the mixture of S1 and mix thoroughly to react; S3. Heat the mixture of S2 to 35°C and mix thoroughly to react; S4. Add water to the mixture in S3 and mix thoroughly; S5. Add hydrogen peroxide to the mixture from S4 until the mixture turns bright yellow. S6. Separate the mixture from S5 and obtain a clear liquid. After dialysis, evaporate and concentrate to obtain the graphene quantum dots.
5. The single-crystal silicon dopant according to claim 1, characterized in that, The ionic liquid includes at least one of imidazole ionic liquids or quaternary ammonium salt ionic liquids; And / or, the solvent comprises a combination of terpineol and deionized water, and the oil-to-water mass ratio of the solvent is 0.35–0.45:0.55–0.
65.
6. The single-crystal silicon dopant according to claim 1, characterized in that, The single-crystal silicon dopant is prepared from the following components by weight percentage: MOFs-5 6%–10%, tri-tert-butylphosphine 3%–5%, graphene quantum dots 1%–5%, starch-based binder 0.5%–1%, ionic liquid 4%–5%, boric acid 5%–10%, ammonium dihydrogen phosphate 3%–7%, polyethylene glycol 5%–8%, with the balance being solvent.
7. The method for preparing single-crystal silicon dopant as described in claims 1 to 6, characterized in that, Includes the following steps: The single-crystal silicon dopant is obtained by thoroughly mixing MOFs-5, tri-tert-butylphosphine, graphene quantum dots, starch-based binder, ionic liquid, boric acid, ammonium dihydrogen phosphate, polyethylene glycol and solvent until homogeneous.
8. A method for preparing single-crystal silicon, characterized in that, The method employs a single-crystal silicon dopant as described in claims 1 to 6, and the preparation method is performed using a pulsed laser.
9. Use of the single-crystal silicon dopant as described in claims 1 to 6 in the semiconductor field.