MXPA00000022A - Transdermal probe with an isotropically etched tip, and method of fabricating such a device - Google Patents

Abstract

A probe (20) includes an elongated body (22) with a top surface (26), a bottom surface (34), a frist sidewall (36) between the top surface (26) and the bottom surface (34), and a second sidewall (38) between the top surface (26) and the bottom surface (34). An end (40) is defined by the bottom surface (34) converging into a tip, an isotropic etched portion of the frist sidewall (36) converging into the tip (34), and an isotropic etched portion of the second wall (38) converting into the tip (34). The elongated body is less than approximately 700 micrometers wide, and less than approximately 200 micrometers thick. The elongated body may incorporate a fluid channel. The elongated body may be formed of silicon that is not doped with boron.

Description

TRANSDERMAL PROBE WITH ISOTROPIC TIP BIT, AND DEVICE MANUFACTURING METHOD BRIEF DESCRIPTION OF THE INVENTION This invention relates, in general, to transdermal probes with ladder scales, such as hypodermic needles, lancets and blades. More specifically. This invention relates to a micrometer-scale transdermal probe that is formed by ordentate or isotropic attack of a mono-crystalline substrate.

BACKGROUND OF THE INVENTION The biomedical industry seeks to replace stainless steel needles for hypodermic injection by needles having small diameters, sharper tips and which can provide additional functionality. The advantages of smaller diameters and sharper tips are to minimize pain and tissue damage. The additional desirable functionality for a hypodermic needle for injection includes the ability to provide integrated electronic circuits for monitoring chemical concentration. The stimulation of the cells and the control of the flow of fluid, as it can be through an integrated valve or pump. The technology of the integrated circuits and micro-platelets of monocrystalline silicon have been used to produce needles for hypodermic injection. A "micro-hypodermic" or "micro-needle" injection needle is described in Lin, et al., "Silicon Processed Microneedle," Digest of Transducers? 93, International Conference on Solid-State Sensors aand Acuators, pp. 622-966. 237-240, June 1993. Another micro needle is described in Chen and Wise, "A Multichannel Neural Probe for Selective Chemical Delivery at the Cellular Level," Technical Digest of the Solid-State Sensor and Actuator orkshop. Hilton head Island S.C., pp. 256-259, June 13-16, 1994. The needles described in these references have common elements since they are based on the process flow for an icroelectric probe. In particular, both processes depend on regions densely contaminated with boron to define the shape of the needle and the use of ethylenediamine pyrocatechol as a reagent for anisotropic attack. Lin et al. describes a passage of fluids that is micromachined on the surface and uses a timed preparation to thin the chip so that a reinforcing rib remains approximately 50 microns thick of monocrystalline silicon. In contrast, Chen and I perform a bulk micromachining of a channel in the micro-needle using an anisotropic preparation and all the monocrystalline silicon containing the needle barrel is densely doped with boron so that the timing of the anisotropic preparation for forming the needle is less crucial. There are some disadvantages associated with these prior art devices. The reinforcing rib of monocrystalline silicon in the micro-needle of Lin, et al., Is naturally rough and difficult to reproduce due to the narrow tolerance on the synchronized attack. Chen's micro-needle and is originated walls of approximately 10 μ or less in thickness and the shape of the fluid channel defines the shape of the silicon comprising the structural portion of the needle. Therefore, small channels give rise to thin needles and long channels give rise to long needles. This is a problem when a needle with a small channel but large cross section in the needle is desired. There is often a need for large cross-sections in the needles, which may be 50 μ in thickness or greater, to obtain a stronger micro-needle, but since the fluid flow rate depends on the cross-section of the needle. needle, a long needle may not provide the necessary resistance to flow. To establish the necessary flow resistance in a large needle section, a complicated nested channel configuration must be fabricated. The micro-needles of Lin et al., And Chen and Wise share the drawback that they depend on the use of boron doping to define the shape of the needle. This requires a prolonged step (approximately 8 hours in Chen and Wise; about 16 hours in Lin), high temperature (approximately 1150 ° C) which is expensive. In addition, the chosen anisotropic attack reagent is ethylenediamine pirocatechol, which is a strong carcinogen, which makes production dangerous and therefore gives rise to other costs. Finally, since both micro-needles use a reagent for anisotropic attack to produce the shape of the micro-needle, limitations are placed on the geometry thereof. In order for the needle to be "sharper", it is preferred that the tip of the needle originate from an almost infinitesimally small point and increase its section continuously without transitions to the full width of the needle body. This geometry is not possible using the techniques described in Lin et al., And Chen and Wise. In particular, needles produced using these techniques have abrupt transitions, largely attributable to the use of reagent for anisotropic attack. Micro-needles that do not include a channel are referred to herein as lancets. The lancets can be used to open the epidermis so that a drop of blood can be sampled. The lancets can also be formed in configurations that allow them to be used as blades or scalpels. These devices can be used to cut the skin or eyes in a surgical context. Thus, as used herein, a transdermal probe refers to micro-needles, lancets or blades (scalpels). It would be highly desirable to provide improved transdermal waves and the manufacturing processes of these probes to monitor the drawbacks associated with prior art devices.

SUMMARY OF THE INVENTION A transdermal probe includes an elongated body with an upper surface, a lower surface, a first side wall between the upper surface and the lower surface, and a second side wall between the upper surface and the lower surface. One end is defined by the bottom surface converging at a tip, an isotropically etched or attacked portion of the first convergent side wall at the tip, and an isotropically etched portion of the second convergent side wall at the tip. The elongate body is less than about 700 μ in width and less than about 200 μ in thickness. The elongated body can incorporate a channel for fluids. The elongated body may be formed of silicon that is not contaminated with boron.

In this configuration, the integrated circuits of a cyrominated device, such as a heater or pump can also be formed in the device. Various novel processing techniques are associated with the manufacture of the device. The device can be formed depending only on the isotropic attack. Otherwise, it is possible to use a combination of isotropic and anisotropic attack. Unlike the micromachined devices of the prior art, the described device can be processed at relatively low temperatures of 1100 ° C or lower without using the carcinogen ethylenediamine pyrocatechol. When a blade is formed, the width can be as wide as about 3 mm and the thickness can be as high as about 400 μ.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the nature and objectives of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which: Figure 1 is a perspective view of a isotropically etched probe according to one embodiment of the invention. Figure 2 is an amplified view of the tips of the probe shown in Figure 1.

Figure 3 is a top view of the probe shown in Figure 1. Figure 4 is a side view of the probe shown in Figure 1. Figure 5 is a front view of the probe shown in Figure 1. FIGURE 6 is a perspective view of an isotropic and anisotroscopically etched probe according to one embodiment of the invention. Figure 7 is an amplified view of the tip of the probe shown in Figure 6. Figures 8a-8e illustrate different etched channels according to the embodiments of the invention. Figures 9a-9e illustrate the construction of a probe according to a first example of the invention. Figures 10a-10i illustrate the construction of a probe according to a second example of the invention. Figures ll-llL illustrate the construction of a probe according to a third example of the invention. Figures 12a-12L illustrate the construction of a probe according to a fourth example of the invention. Figures 13a ~ 13q 'illustrate the construction of a probe according to a fifth example of the invention. Figures 14a ~ 14m 'illustrate the construction of a probe according to a sixth example of the invention.

Figures 15a-15m / illustrate the construction of a probe according to a seventh example of the invention. Figures 16a-16o 'illustrate the construction of a probe according to an eighth example of the invention. Figures 17a-17f illustrate the construction of a probe according to a ninth example of the invention. Figures 18a-18h illustrate the construction of a probe according to a tenth example of the invention. Figures 19a-19i illustrate the construction of a probe according to a tenth example of the invention. Figures 20a-20f illustrate the construction of a probe according to a twelfth example of the invention. Figures 21 illustrates the attack speed of the reagent for isotropic attack of PSG deposited using different phosphine flow rate parameters according to the invention. Figures 22a-22b are perspective views of lancets constructed in accordance with the invention. Figure 23 illustrates a raider constructed in accordance with one embodiment of the invention. Figure 24 is an enlarged view of the isotropically etched tips associated with the raiser of Figure 23.

Figure 25a-b illustrates the construction of a razor with sharp tips according to a thirteenth example of the invention. Figures 2a-b illustrate the construction of a flat-tipped raiser according to a fourteenth example of the invention. Figure 27a-e illustrates the construction of a raider with pyramidal projections according to a fifteenth example of the invention. Like reference numbers refer to corresponding parts in all the different views of the drawings.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 provides a perspective view of an isotropically etched transdermal probe 20 according to one embodiment of the invention. The probe 20 includes an elongated body 22, formed of monocrystalline material, preferably silicon, ending at a handle end 24.

The elongate body 22 has an upper, preferably horizontal, surface 26. In the embodiment of Figure 1, the upper surface 26 has a channel cover 28, which includes an inlet / outlet port of the channel 30 and an outlet port. / channel 32. As will be shown in the following, the embodiments of the probe of the invention include a channel formed integrally within the elongate body 22. The channel cover 28, which may be formed with polycrystalline silicon, covers the channel. The inlet port of the channel cover 30 allows fluid to enter the channel, and the outlet port of the channel cover 32 allows the fluid to exit the channel. In this configuration, the probe 20 of the invention can be used to deliver or withdraw fluid from a vessel, or it can be a living body or a container of medicament. The modalities of the probe 20 do not include a channel, these modalities are useful as lancets, which are used to open the human tissue for the purpose of drawing blood. In other embodiments of the invention, the probe can be used as a blade. The elongated body 22 also includes a lower, preferably horizontal, surface 34. Connected between the upper surface 26 and the lower surface 34 is a first side wall 36 and a second side wall 38. In the embodiment of Figure 1, each wall Lateral has a curved shape attributable to an isotropic etching operation, which is described below. Figure 2 is an enlarged view of the distal or tip end 40 of the elongate body 22. The figure illustrates the top surface 26, the channel cover 28, the outlet port of the channel cover 32, the bottom surface 34, the first side wall 36 and second side wall 38. noting that the bottom surface 34 converges at the tip 40. In particular, the horizontal bottom surface 34 converges in the horizontal direction at the tip 40. Since isotropic etching techniques are used, Tip 40 can be almost infinitesimal small. Figure 2 also illustrates that the first side wall 36 converges at the tip 40, as does the second side wall 38. In particular, each side wall 36 and 38 converges horizontally and vertically at the tip 40 in a smooth, non-stepped manner of Transition. The first side wall 36 and the second side wall 38 meet each other to form a rib 42, which extends smoothly toward the tip 40. The tip 40 formed in accordance with the present invention is sharper than the prior art probes. because the processing to form the tip provides a tip that originates from an almost infinitesimal point that increases its section for the full dimensions of the elongate body 22. Figure 3 is a top view of the isotropically etched probe 20. The figure clearly shows the above-described elements, including the handle end 24, the upper surface 26, the channel cover 28, the inlet port of the channel cover 30, the exit port of the channel cover 32, the first side wall 36, the second side wall 38 and the tip 40.

Figure 4 is a side view of the probe 20. The figure shows the handle end 24, the top surface 26, the channel cover 28, the bottom surface 34, the first side wall 36 and the tip 40. Note the curved surface which gives rise to tip 40. This smooth surface, without abrupt transition steps, is attributable to the isotropic etching operation and used according to the invention. Figure 5 is a front view of the probe 20. The figure shows the handle end 24, the top surface 26, the channel cover 28, the bottom surface 34. The figure also shows the curved side walls 36 and 38. The walls curves avoid abrupt transition steps associated with prior art probes. The curved side walls are attributable to the isotropic etching operation of the invention. Figure 6 is a perspective view of an isotropic / anisotropically etched probe 50 according to another embodiment of the invention. The probe 50 includes an elongated body 52 that terminates at a handle end 54. The device includes a horizontal top surface 56, which supports a channel cover 58. The channel cover 58 includes a cover inlet port at channel 60 and an exit port of the deck on channel 62.

Figure 6 also shows a first vertical side wall 66, positioned between the horizontal top surface 56 and a horizontal bottom surface 64. A second vertical side wall (not shown) exists on the other side of the device. Figure 7 is an enlarged, perspective view of the distal end or tip 70 of the elongate body 52. Figure 7 clearly shows the vertical side wall 66, which contrasts with the curved side walls of the device of Figures 1-5. Tip 70 is formed using a combination of isotropic and anisotropic etching. The anisotropic etching provides the vertical side walls, while the isotropic etching provides smooth transition to the tip 70. The tip has smooth surfaces and otherwise abrupt transitions, gaps between the tip 70 and the transverse area of the elongate body 52. Figures 8a-8e illustrate different isotropic and anisotropically etched channels according to different embodiments of the invention. Figure 8a illustrates an isotropically etched probe 20 with isotropically routed sidewalls 36 and 38. The figure also shows a polysilicon cover 28. Figure 8b is a similar figure, but shows a channel 72 formed with an anisotropic reagent for a silicon plate (100). Figure 8c shows a channel 72 formed with a reagent for isotropic attack. Figure 8d shows an isotropically etched channel 74 with a flat bottom. Finally, Figure 8e shows a channel 76 that is vertically etched. As will be demonstrated below, the invention can be made using a wide variety of processing techniques. The examples provided herein are for the purpose of illustration. The invention in no sense should be considered as limited to the examples described. Not only have a large number of processing techniques been used to perform the invention, but a variety of device sizes have also been used. For example, the devices of Figures 8a-8e were made as devices 330 μ wide and 100 μ thick. The elongate body 52 of Figure 6 has been made as a device with 100 μ in its square cross section. A jagged hole in the vertical direction, formed through an alignment and etching technique on two sides, has given rise to devices with 290 μ of width and 100 μ of thickness. Alignment and etching on two sides on a chip with standard thickness (500 μ) has produced devices that are 640 μ wide and 120 μ thick. In general, the invention is made with an elongate body having less than about 700 μ in width and less than about 200 μ in thickness. More preferably, the invention is made with an elongate body having less than about 300 μ in width and less than about 150 μ in thickness. In the case of a blade, the width of the blade may be about 3 mm, and its thickness may be as high as 400 μ. For convenience, many of the processing techniques described in the following use silicon wafers on an insulator (SOI). The fabrication of the probes using the SOI chips greatly simplifies processing. The type of SOI chips commonly used to manufacture the probes described in the application are composed of two silicon wafers that are linked together by an intermediate insulating material, usually silicon dioxide. The upper chip (device chip) is thinned to the desired thickness of the probe using a combination of grinding and polishing techniques. The function of the lower chip (handle microplate) is to provide a strong substrate for easy handling. Since the manufacture of the probe is done only on the layer of the device, the purpose of the insulating material is to provide a chemical etch suppressor to prevent etching in the handle layer.

Suppliers can provide SOI chips with specified total thickness, a specified device layer thickness and a specified thickness for the insulating layer. The availability of SOI chips allows the use of standard integrated circuit processing equipment since the total thickness of the chip is equal to a normal chip. Also, the thickness of the needles can be better controlled since the SOI chip suppliers can guarantee a layer thickness for the device within some microns and this thickness is known before processing. In addition, slimming steps of the chip are not required, which are a common cause of variations in the thickness of the probe, beyond the variations of the SOI chip provider nor is it required with boron or EDP to define the form of the probe. Finally, since the insulating layer provides a chemical etch suppressor, the synchronization of the chemical attack is not crucial. As described below, the following processing steps have been used to build different devices, according to the invention. Those skilled in the art will appreciate that a variety of modifications are possible in the specified steps, and still be within the scope of the invention.

TABLE 1 - PREFERRED MANUFACTURING STEPS CLEANING THE MICROPLAQUE TO STANDARD Use a VLSI lab board Clean with Piranha (H2SO4.H2O2, 5: 1) for 10 minutes Two one minute rinses in deionized water (DI) Rinse until water resistivity is> 11 MO-cm Dry by centrifugation Clean with Piranha (H2S? 4: H2? 2, 5: 1) for 10 minutes at 120 ° C Rinse in DI water for one minute. Immerse in HF 25: 1 until it is hydrophobic. Two one minute rinses in DI water. Rinse until the resistivity of the DI water is > 14MO-cm Dry by centrifugation CLEANING MICROWAVES WITH MINIMAL RUST TRAY Use VLSI lab board Clean with Piranha (H2S? 4: H202, 5: 1) for 10 minutes Rinse with DI water for one minute. Immerse in HF 25: 1 briefly until the native silicon oxide is removed. Two one minute rinses in DI water. Rinse until the resistivity of the DI water is > 1 < MO-cm Dry by centrifugation PARTIALLY CLEAN MICROWATERS Use VLSI lab board Clean with Piranha (HS ?: H2? 2, 5: 1) for 10 minutes Two one minute rinses in DI water Rinse until the resistivity of the DI water is > eleven MO-cm Dry by centrifugation LOW VOLTAGE SILICON NITRIDE TANK Use a low pressure, chemical vapor deposition reactor, horizontal Direct thickness as specified Conditions = 835 ° C, 140 mTorr, 100 sccm DCS, and 25 sccm NH3 GLOSS TANK PHOSPHOSYLLATE (PSG) Use an ector for the chemical vapor deposition, low pressure, horizontal Direct thickness as specified Conditions - 450 ° C, 300 mTorr, 60 sccm SÍH4, and 90 sccm 02 and 5.2 sccm PH3 G. DENSIFY WITH LPCVD OXIDE.

LOW TEMPERATURE OXID DEPOSIT (LTO) Use a low pressure, chemical vapor deposition reactor, horizontal Direct thickness as specified Conditions = 450 ° C, 300 mTorr, 60 sccm SiH4, and 90 sccm 02 G. DENSIFY WITH LPCVD OXIDE.

DENSIFY LPCVD OXIDE Use a reactor at atmospheric pressure, horizontal Conditions = 950 ° C, N2, 1 hour; otherwise, 1100 ° C with a current environment instead of N2 PHOTOLITOGRAPHY 1. HMDS primer 2. Photoresist coating: cover 1 μ of Shipley S3813 (it may be necessary to vary the thickness depending on the topography and thickness of the material to be attacked) positive protective material at multiple wavelengths 3. Expose the Protective material: G-line stepped chip, normal exposure time 4. Protective matter development: standard development using Shipley MF319 5. Intense baking for 30 minutes I. REAR COVERING WITH PHOTORRESISTENT MATERIAL 1. HMDS primer 2. Photoresist coating: coat 1 μ of Shipley S3813 (it may be necessary to vary the thickness depending on the topography and thickness of the material to be attacked) positive protective material multiple wavelengths 3. Development of photoresist: normal development used Shipley MF319 4. Intense baking for 30 minutes J. MIXED IN OXIDES MOISTURE Use VLSI laboratory tablet Perform the chemical attack in NHF 5: 1 until the desired amount of oxide has been removed Two one minute rinses in DI water Rinse until the water resistivity is> 0. 11MO- cm Drying by centrifugation K. ELIMINATION OF PHOTORRESISTENT MATERIAL Use PRS-2000 laboratory bench, heated at 90 ° C, 10 minutes, Rinse in three DI water baths, 2 minutes at a time C. PARTIAL CLEANING OF MICROWAVES BITING WITH NITRIDE Performing the chemical attack with SFg + plasma of He Perform the chemical attack until the desired amount of nitride has been eliminated M. UNPURIFIED POLYSILITIC DEPOSIT Use reactor to deposit chemical vapors, low pressure, horizontal Direct the thickness as specified Conditions = 6Q5 ° C, 555 mTorr, and 125 sccm YESH4; otherwise, 580 ° C, 300 mTorr, and 100 sccm SiH4 N. CHEMICAL POLYSILITIC ATTACK Perform the chemical attack with chlorine plasma Perform the chemical attack until the desired amount of polysilicon has been eliminated O. ISOTROPIC CHEMICAL ATTACK OF THE SILICON Use laboratory scale Immerse in reagent for chemical attack of silicon (64% HN? 3/33% H20 / 3% NH4F) until the desired amount of silicon has been removed Rinse in DI water for 1 hour (Different concentrations of CH4F will work.) In addition, there are multiple reagents for isotropic chemical attack including HF, HNO3 and C2H2 and reagents for chemical attack including HF, HNO3, XeF2, SF§ and H20 which can be used in the context of the invention.) ANISOTROPIC CHEMICAL ATTACK IN HUMID Use laboratory jar, heated bath 750 g of KOH: 1500 ml of H20; multiple concentrations of KOH can be used to obtain faster or slower attack rates and higher / lower silicon selectivity on the oxide Temperature 80 ° C CHEMICAL ATTACK IN MOISTURE FOR THE ELIMINATION OF OXIDE Use laboratory bench Perform the chemical attack in diluted HF or buffered HF until the desired oxide is eliminated Rinse in deionized water for approximately 1 hour R. CHEMICAL ATTACK FOR THE FORMATION OF A WALL WITH WALLS ALMOST VERTICAL Use the inductively coupled plasma chemical reagent Advanced process for chemical attack of silicon Low pressure processing system, high density plasma Fluorine plasma Perform the attack at the desired depth S. CHEMICAL ATTACK OF OXIDE, PSG AND SILICON NITRIDE Use laboratory scale Immerse in concentrated HF with surfactant if necessary, continue until the desired sacrificial material is removed Rinse for 2 minutes in two tanks of DI water Rinse for 120 minutes in a third DI water tank T. SPRAY OR DEPOSIT GOLD Use a low pressure camera Carry out the gold U. GOLD CHEMICAL ATTACK Use laboratory jar Reagent for water regia attack or other reagent for commercially available gold attack V. OXIDATION IN HUMID Use reactor at atmospheric pressure, horizontal Conditions = temperature as specified, environment with water vapor . DIFFUSION OF THE BORE Use reactor at atmospheric pressure, horizontal Diffusion of boron from solid source Conditions = temperature as specified X. POLYSILITIZE TANK IMPURIED ON SITE Use reactor for chemical vapor deposition, low pressure, horizontal Target thickness as specified Conditions = 610 ° C and 300 mTorr Y. THERMAL OXIDATION Use reactor at atmospheric pressure, horizontal Conditions = 1050 ° C, atmosphere with steam MICROPLAQUETAS UNIDAS BY FUSIÓN Reactor at atmospheric pressure, horizontal Conditions = 1100 ° C, environment with nitrogen EXAMPLE I Figures 9a-9e illustrate the process flow to construct an isotropically etched probe fabricated on a silicon on insulation chip (SOI). Figure 9a illustrates a SOI 90 chip that includes an insulating layer 92 sandwiched between a chip of the device 94 and a grip chip 96. The chip device 94 is formed of monocrystalline silicon with a thickness of about 100 μ. The orientation is (100) or (110). Insulator 92 is Si02 thermally developed, which is 1 to 2 μ thick, but can also be silicon nitride and / or chemically deposited oxide. The handle chip 96 is monocrystalline silicon of approximately 500 μ thickness with an orientation (100). Since the handle chip 96 is formed of monocrystalline silicon it has the same shading as the chip of the device 94, which is also formed of monocrystalline silicon. After cleaning the chip 90 (step A), a layer of approximately 0.5 μ thickness of silicon nitride is deposited (step D). The silicon nitride 98, shown in Figure 9b, serves as a masking material for the isotropic chemical attack of silicon. The silicon nitride 98 is then modeled (step H), the etching is performed (step L), and the photoresist material is removed (step K). The resulting structure is shown in Figure 9c. Subsequently, the device is immersed in the reagent for silicon isotropic attack (step O), producing the device as shown in Figure 9d. Note that this operation produces smooth sidewalls 36 and 38 of the type shown in Figures 1-5. It should be appreciated that Figures 9a-9e are a front-cut view of the probe 20 at approximately the center of the elongated body 22. The same processing generates the above-described tip 40. Then the silicon nitride is removed and the probe (step S). Figure 9e illustrates the released probe 20. The device is then rinsed in deionized water for about 1 hour. The resulting device, which does not include a channel, is a probe for use as a lancet.

EXAMPLE II FIGS. 10A-10O illustrate the process flow for building an etched isotropic probe with a micromachined fluids channel on the surface made on a SOI chip. Figure 10a illustrates a device of the type shown and described with reference to Figure 9a. The chip is cleaned (step A). Then a phosphosilicate glass layer approximately 2 μ thick is deposited (step E). Figure 10b shows the phospho-silicate glass 100, which is used as a sacrificial material for the channel. The phosphosilicate glass 100 is then molded (step H), etched (step J), and the photoresist material (step K) is detached to form the mold to make the fluid channel. The resulting device is shown in Figure 10c. The device is then cleaned (step B) and a layer of polysilicon of approximately 2 μ (step M) is deposited to form the chassis material of the channel cover. The polysilicon 102 is shown in Figure 10Od. The polysilicon 102 is then molded (step H), the chemical attack is carried out (step N), and the protective material is removed (step K). This gives rise to the inlet port of the channel cover described above and to the outlet port of the channel cover. In addition, this operation removes the polysilicon from the edges of the cover. The resulting structure is shown in Figure 10. The region 32 between the two elements of polysilicon 102 is the output port of the channel cover. The chip is then cleaned (step B). Then a layer of 0.5 μm thick silicon nitride is deposited (step B). The silicon nitride 98, shown in Figure 10OF, functions as a masking material for the isotropic chemical attack of silicon. The silicon nitride 98 is then molded (step H), the chemical attack is performed (step L), and the protective layer is removed (step K) giving rise to the device shown in Figure 10Og. The device is then immersed in a reagent for isotropic silicon attack (step O). Producing the device shown in Figure 10. Once again observe the first and second curved side walls 36 and 38 formed by this operation. This operation also produces the structure of the tip described above. The silicon nitride is then removed (step S), the probe is released and the phosphosilicate glass is removed to produce the device shown in Figure 10. The device is then rinsed in deionized water for about 1 hour.

EXAMPLE III Figures ll-llL illustrate the process flow for an isotropically formed probe incorporating an anisotropic etchant reagent to form a channel, as manufactured on a SOI chip. The initial device of Figure 11 is of the type described in the previous examples. The chip is cleaned (step A) and approximately 0.5 μ of silicon nitride is deposited (step D), originating the device shown in Figure 11b. Otherwise, a 0.5 μ thick layer of thermal oxide can replace the 0.5 μm thick silicon nitride layer. The oxide layer is attacked using the reagent for chemical attack CF4 + CHF3 + He plasma and solution of H20: KOH 4: 1 at 40 ° C. Then the silicon nitride is molded (step H), the chemical attack is carried out (step L), and the protective layer is removed (step K). then the monocrystalline silicon (100) is subjected to an anisotropic attack reagent (step B) to form an anisotropically etched pit 72 for a fluid passage, as shown in Figure 11c. Then the chip is cleaned (step A) and about 2 μ of phosphosilicate glass is deposited (step E) to fill the holes in the silicon nitride masking layer 98, as shown in Figure lid. It may be preferable to make a deposit of 3 μ thickness of PSG and densification at a higher temperature of the PSG compared to that specified in step G. A more stable densification is 2 hours, 1100 ° C in an ambient stream. Since it is desirable to minimize the high temperature steps in cases where circuitry is included, densification should be performed at temperatures closer to 950 ° C. The phosphosilicate glass 100 is then molded (step H), etched (step J) and the protective layer (step K) is removed to expose the silicon nitride 98 regions, as shown in Figure Lie.

Then the silicon nitride 98 is etched (step L), giving rise to the device shown in Figure llf. The protective layer can usually be removed before attacking the nitride since the phosphosilicate glass acts as a mask for the reagent for attack. In some cases, the thickness of the phosphosilicate glass may not be thick enough to prevent the reagent from attacking the underlying nitride, in which case a photoresist material may be necessary. Then the chip is cleaned (step B), then approximately 2 μ of polysilicon (step M) is deposited to form the chassis material of the channel cover, giving rise to the device shown in Figure llg. The device is then molded (step H), etched (step N), and the photoresist material (step K) is removed to form the inlet and outlet ports of the channel cover and to remove the polysilicon from the edge of the cover . This processing gives rise to the device shown in Figure llh. The chip is then cleaned (step B) and deposited to approximately 0.5 μ of silicon nitride (step D). Silicon nitride 98, as shown in Figure 11, is used as the masking material for the isotropic chemical attack of silicon. The silicon nitride is then molded (step H), the chemical attack is performed (step L), and the protective material is removed (step K), giving rise to the structure shown in Figure llj. Then the device is immersed in a reagent for isotropic silicon attack (step 0), producing the structure of Figure 11. Then the silicon nitride is removed, the probe is released and the phosphosilicate glass is removed (step S). The resulting device, shown in Figure 11L, is then rinsed in deionized water for about 1 hour.

EXAMPLE IV Figures 12a-12L illustrate the process flow for an isotropically formed probe incorporating an isotropic chemical attack reagent to form a channel, as manufactured on a SOI chip. The initial device of Figure 12a is of the type described in the previous examples. The chip is cleaned (step A) and about 0.5 μ of silicon nitride is deposited (step D), giving rise to the device shown in Figure 12b. The silicon nitride is then molded (step H), the chemical attack is carried out (step L), and the protective material is removed (step K). then the monocrystalline silicon (11) is subjected to an isotropic attack reagent (step O) to form a flat bottom, isotropically etched pit 74 for a fluid passage, as shown in Figure 12c. Then the chip is cleaned (step A) and about 2 μ of phosphosilicate glass is deposited (step E) to fill the holes in the silicon nitride masking layer 98, as shown in Figure 12d. The fssphosilicate glass 100 is then molded (step H), the etching is performed (step J) and the protective material is removed (step K) to expose the silicon nitride regions 98, as shown in Figure 12e. Then the silicon nitride 98 is etched (step L), giving rise to the device shown in Figure 12f. Typically, the protective material can be separated before the attack of the nitride since the phosphosilicate glass acts as a mask for the reagent for attack. In some cases, the thickness of the phosphosilicate glass may not be thick enough to prevent the reagent from attacking the underlying nitride, in which case a photoresist material may be necessary. Then the chip is cleaned (step B). Then approximately 2 μ of polysilicon (step M) is deposited to form the material chassis of the fluid channel, giving rise to the device shown in Figure 12g. Then the device is molded (step H) the chemical attack is carried out (step N), and the photoresist material (step K) is removed to form the fluid inlet and outlet port and to remove the polysilicon from the edge of the cover. This processing gives rise to the device shown in Figure 12h. The chip is then cleaned (step B) and about 0.5 μ of silicon nitride is deposited (step D). The silicon nitride 98, as shown in Figure 12i, is used as the masking material for the reagent for isotropic silicon attack. Then the silicon nitride is molded (step H), the chemical attack is carried out (step L), and the protective matter is removed (step K) giving rise to the structure shown in Figure 12. The device is then immersed in a reagent for silicon isotropic attack (step O), producing the structure of Figure 12k. Then the silicon nitride is removed, the probe is released and the phosphosilicate glass is removed (step S). The resulting device shown in Figure L is then rinsed in deionized water for about 1 hour.

EXAMPLE V Figures 13a-13qf illustrate the process flow for an isotropically formed probe incorporating an anisotropic reagent to form a channel fabricated on a SOI chip with integrated circuits and a micromachined structure in the form of a polysilicon heater. In the following figures, the Figures on the left side of each page are cross sections of the axis, while the figures on the right side of each page are cuts of the circuits. Figure 13a is a SOI chip with orientation (100). The left side of Figure 13a 'illustrates two impurified regions p + 120 and 122. A polysilicon contact 124 is placed on each region. A polysilicon region n + 126 is placed between the contacts 124. The right side of Figure 13a 'has a similar configuration, but also includes a wall n 130 and regions n + 132, The processing used to construct such a device it is known in the art. The chip is cleaned (step B) and about 0.5 μ of silicon nitride is deposited (step D), giving rise to the structure shown in Figures 13b and 13b '. The chip is then cleaned (step B) and about 0.4 μ of polysilicon (step X) is deposited to form a polysilicon heater. The polysilicon is molded (step H), the chemical attack is carried out (step N), and the protective matter is removed (step K). Then the chip is cleaned (step B). Then approximately 0.5 μ of silicon nitride (step D) is deposited to protect the polysilicon during the chemical attack of silicon. The resulting structure is shown in Figures 13c and 13c '. The silicon nitride is then molded (step H), the chemical attack is carried out (step L), and the protective matter is removed (step K). (A more compatible attack reagent IC of tetramethyl ammonium hydroxide can be used in place of KOH). The chemical attack of the monocrystalline silicon is then carried out in an anisotropic attack reagent (step P) to form a pit for a fluid passage, as shown in Figure 13b. The chip is then cleaned (step A) and about 2 μ of phosphosilicate glass is deposited (step E) to fill the holes in the silicon nitride masking layer. The resulting structure is shown in Figures 13e and 13e '. Then the device is molded (step H), the chemical attack is carried out (step J), and the protective material is removed (step K). This exposes regions of the silicon nitride, as shown in Figures 13f and 13f '. The silicon nitride is then molded (step H), the chemical attack is carried out (step L), and the protective matter is removed (step K). This operation removes the nitride from the region outside the channel and over the electrical contact holes, as shown in Figures 13g and 13g '. The chip is then cleaned (step B) and about 2 μ of polysilicon (step M) is deposited to form the material of the fluid channel., as shown in Figures 13h and 13 '. The polysilicon is then molded (step H), the chemical attack is carried out (step N), and the protective matter is removed (step K). The operation produces the inlet and outlet ports of the carcass cover and removes the polysilicon from the edges of the deck. The resulting structure is shown in Figures 13i and 13i '. The chip is then cleaned (step B) and approximately 0.4 μ of polysilicon (step M) is deposited to form a thin protective layer on the electrical contacts during a chemical attack with subsequent HF. This gives rise to the structure of Figures 13j and 13j '. The polysilicon is then molded (step H), the chemical attack is carried out (step N) and the protective matter is removed (step K). This gives rise to the elimination of polysilicon that is not covering the circuits, as shown in Figures 13k and 13k '. Then the chip is cleaned (step B) and about 0.5 μ of silicon nitride is deposited (step D). The silicon nitride, shown in Figures 13L and 13L ', is used as the masking material for the isotropic chemical attack of silicon. The silicon nitride is then molded (step H), the chemical attack is carried out (step L), and the protective matter is removed (step K). This gives rise to the structure of Figures 13m and 13m '. The device is then immersed in the reagent for silicon isotropic attack (step 0) producing the structure of Figures 13n and 13n '. The microplate is then immersed in HF (step S), to remove most of the silicon nitride, the probe is released and the phosphosilicate glass is removed. The resulting structure is shown in Figures 13o and 13o '. Some of the silicon nitride must remain to isolate the heaters from the substrate so that the timing of the chemical attack with HF is important. Then the microplate is rinsed with deionized water for about 1 hour. Then a short chemical attack of the silicon is made with plasma (step N) to remove the thin, protective layer of the polysilicon over the circuits. This operation results in the device of Figures 13p and 13p '. The final step is a rapid dip in hydrofluoric acid to remove the oxide covering the polysilicon contacts (step Q). The final structure is shown in Figures 13q and 13q '.

EXAMPLE VI Figures 14a-14m 'illustrate the process flow for an isotropically formed probe incorporating an anisotropic chemical attack to form a channel. The process uses a thin chip with circuits and etching on two sides. In the following figures, the figures on the left side of each page are cuts on the axis of the probe, while the figures on the right side of each page are cuts on the circuits. Figure 14a shows a silicon p-type chip (100) that is approximately 100 μ thick. Figure 14a 'shows a structure of the type described with reference to Figure 13a', but without layers 92 and 96 of Figure 13a '. The chip is cleaned (step B). Then approximately 0.5 μ of silicon nitride is deposited (step D). The resulting structure is shown in Figures 14b and 14b '. The silicon nitride is then molded (step H), the chemical attack is carried out (step L), and the protective matter is removed (step K). The chemical attack of the monocrystalline silicon is then carried out in an anisotropic reagent reagent (step P) to form the pit for the luid passage. • The resulting structure is shown in Figures 14c and 14c '. The chip is then cleaned. { step A) and about 2 μ of phosphosilicate glass is deposited (step E) to fill the holes in the silicon nitride coating layer. The resulting structure is shown in Figures 14d and 14d '. Then the phosphosilicate glass is molded (step H), the chemical attack is carried out (step J), and the protective matter is removed (step K). This causes the formation of a mold to make the cover in fluids channel. Then the silicon nitride attack is carried out (step L). The resulting structure is shown in Figures 14e and 14e '. Typically, the protective material can be removed before the chemical attack of the nitride since the phosphosilicate glass acts as a mask of chemical attack. In some cases, the thickness of the phosphosilicate glass may not be so thick to prevent the reagent from attacking the underlying nitride, in which case a photoresist material may be necessary. The microscrollette is then cleaned (step B) and approximately 2 μ of polysilicon (step M) is deposited to form the material of the fluid channel frame. The resulting structure is shown in Figures 14f and 14f '. The polysilicon is then molded (step H) and the chemical attack is carried out (step N) to form the fluid inlet and outlet ports and to remove the polysilicon from the edge of the cover. The polysilicon is then removed from the back side of the chip (step N) and the protective matter is removed (step K). The resulting structure is shown in Figures 14g and 14g '. The chip is then cleaned (step B) and about 0.5 μ of silicon nitride (step D) is deposited to function as a masking material for the isotropic chemical attack of silicon. Figures 14h and 14h 'show the resulting structure. Then the silicon nitride is molded (step H), the chemical attack is carried out (step L), and the protective matter (step K) is removed to generate the structure shown in Figures 14i and 14i '. The silicon nitride of the electrical contacts is then molded (step H) and the chemical attack of the silicon nitride layer is carried out (step L), the attack of the polysilicon layer is carried out (step N), the Attack of the silicon nitride layer (step L) and the chemical attack of the oxide layer (step Q) is performed to expose the electrical contacts as shown in Figure 14j '. Then the protective matter is removed (step K). Then the chip is cleaned (step B) and gold is sprayed (step T) on the front side of the chip. Preferably a chromium adhesion layer is used. The gold is molded (step H), the chemical attack is carried out (step U), and the protective matter is removed (step K). The resulting gold bags are shown in Figure 14k '. The microplate is then immersed in a reagent for isotropic attack (step 0) producing the structure of Figures 141 and 141 '. The microplate is then immersed in HF (step S) to remove the silicon nitride, the probe is freed and the phosphosilicate glass is removed. The chip is then rinsed in deionized water for about 1 hour to produce the structure shown in Figures 14m and 14m '.

EXAMPLE VII Figures 15a-15m 'illustrate the process flow for an isotropically formed probe incorporating an anisotropic chemical attack to form a channel. The process uses a chip of standard thickness with circuits and chemical attack on both sides. In the following figures, the figures on the left side of each page are the cuts of the probe axis, while the figures on the right side of each page are cuts of the circuits. Figure 15a shows a silicon p-type chip (100) that is about 15 μ thick. Figure 15a 'shows a structure of the type described with reference to Figure 13a', but without the layers 92 and 96 of Figure 13a '. The chip is cleaned (step B) and about 0.5 μ of silicon nitride is deposited (step D), resulting in the structure of Figures 15b and 15b '. The silicon nitride is then molded (step H), the chemical attack is carried out (step L), and the protective matter is removed (step K). The chemical attack of the monocrystalline silicon is then carried out in an anisotropic attack reagent (step P) to form a fluid passage pit, as shown in Figure 15c. The chip is then cleaned (step B) and about 2 μ of phosphosilicate glass is deposited (step E) to fill the holes in the silicon nitride masking layer. The resulting structure is shown in Figures 15d and 15d '. The fssfosilicate glass is then molded (step H), the chemical attack is carried out (step J), and the protective matter is removed (step K). This forms the mold to make the channel cover for fluids. Then the chemical attack of the silicon nitride is carried out (step L), giving rise to the structure shown in Figures 15e and 15e '. The protective matter can usually be removed before the chemical attack of the nitride since the phosphosilicate glass acts as a mask for chemical attack. In some cases, the thickness of the phosphosilicate glass may not be so thick to prevent the reagent from attacking the underlying nitride, in which case a photoresist material may be necessary. The chip is then cleaned (step B) and about 2 μ of polysilicon (step M) is deposited to form the frame material as shown in Figures 15f and 15f '. The polysilicon is then molded (step H) and the chemical attack is carried out (step N) to form the entrance and exit port of the carcass cover, to eliminate the polysilicon from the edge of the cover, and to eliminate the polysilicon from the back side of the chip (step N). Then the protective material is removed (step K). The resulting structure is shown in Figures 15g and 15g '. Then the chip is cleaned (step B) and about 0.5 μ of silicon nitride is deposited (step D). The silicon nitride serves as a masking material for the isotropic chemical attack of silicon. The silicon nitride layer is shown in Figures 15h and 15h '. The silicon nitride is molded (step H), the chemical attack is carried out (step L) and the protective matter is eliminated (step K). This gives rise to the structure shown in Figures 15i and 15i '. Then a pattern is applied over the electrical contacts (step H). Then the chemical attack on the silicon nitride layer is carried out (step L), the chemical attack of the polysilicon layer is carried out (step N), the chemical attack is carried out on the silicon nitride layer (step L), and the chemical attack on the oxide layer is carried out (step Q). Then the protective matter is removed (step K). The resulting structure is shown in Figures 15j and 15j '. Then the chip is cleaned (step B) and the gold is sprayed (step T) on the front side of the chip. The gold pattern is formed (step H), the chemical attack is performed (step U), and the protective matter (step K) is removed to produce the structure of Figures 15k and 15k '. It may be necessary to deposit additional adhesion layers such as titanium or chromium before depositing the gold.

The microplate is then immersed in a reagent for silicon isotropic attack (step O), to produce the structure of Figures 151 and 151 '. The microplate is then immersed in HF (step S) to remove the silicon nitride, the probe is freed and the phosphosilicate glass is removed. The microplate is then rinsed in deionized water for about 1 hour. The final structure is shown in Figures 15m and 15m '.

EXAMPLE VIII Figures 16a-16o 'illustrate the process flow for an anisotropic and isotropically formed probe incorporating an anisotropic chemical attack to form the channel. The device is manufactured on a SOI chip with an upper layer (110). The processing is used to build a device of the type shown in Figures 6-7. The figures on the left side of the page show the cut of the region of the tip, while the figures on the right side of the page show the cut of the region of the axis of the probe. Figures 16a and 16a 'show a silicon chip (110) attached to oxide on a silicon chip. The chip is cleaned (step A) and approximately 0.5 μ of silicon nitride (step D) is deposited resulting in the device shown in Figures 16b and 16b '. Then the pattern is formed in the silicon nitride (step H), the chemical attack is carried out (step L), and the protective matter is removed (step K). The monocrystalline silicon is then subjected to an anisotropic attack reagent (step P) to form the pit for the passage of fluids, giving rise to the device of Figures 16c and 16c '. The chip is then cleaned (step A) and deposited to approximately 2 μ of phosphosilicate glass (step E) to fill the holes in the masking layer of the silicon nitride, as shown in Figures 16d and 16d '. Then the phosphosilicate glass is molded (step H), the chemical attack is carried out (step J), and the protective matter is removed (step K) This operation exposes regions of silicon nitride, as shown in Figures 16e and 16e '. The attack is then performed on the silicon nitride (step L) to produce the structure of Figures 16f and 16f. In general, the protective layer can be removed before the chemical attack of the nitride since the phosphosilicate glass acts as a mask for chemical attack. In some cases, the thickness of the phosphosilicate glass may not be so thick to prevent the reagent from attacking the underlying nitride, in which case a photoresist material may be necessary. Then the chip is cleaned (step B) and about 2 μ polysilicon (step M) is deposited to form the material of the fluid channel frame. The resulting structure is shown in Figures 16g and 16g '. The polysilicon is then molded (step H) and the chemical attack is carried out (step N) to form the inlet and outlet ports of the channel cover. The protective matter is then removed (step K). This gives rise to the device of Figures 16h and 16h '. Then, the microplate (step B) is cleaned and approximately 0.5 μ of silicon nitride is deposited (step B), as shown in Figures 16i and 16i '. The silicon nitride functions as a masking material for the isotropic chemical attack of silicon. The silicon nitride is molded (step H), the chemical attack is carried out (step L), and the protective matter is removed (step K). This results in the structure of Figures 16j and 16j '. Then the chip is cleaned (step A) and approximately 2 μ of oxide is deposited at low temperature (step F) for the masking material of the anisotropic chemical attack. An alternative masking material is polyhexane or even an additional layer of silicon nitride. The deposited substance is molded (step H), the chemical etching is carried out (step J) and the protective matter (step K) is removed to produce the structure of Figures 16k and 16k '. Then chemical attack of the monocrystalline silicon is carried out in an anisotropic attack reagent (step P) to form vertical walls along the axis of the probe, as shown in Figures 161 and 161 '. Then, the mask of the reagent for anisotropic attack of silicon, oxide at low temperature (step Q) is removed to generate the structure of Figures 16m and 16m '. The microplate is then immersed in a reagent for silicon isotropic attack (step O) to produce smooth, converging surfaces at the tip, as shown in Figure lßn. The chip is then immersed in HF (step S) to remove the silicon nitride, release the probe and remove the phosphosilicate glass, as shown in Figures 16o and 16o '. The microplate is then rinsed in deionized water for about 1 hour. The techniques of the invention can also be used in connection with chips of standard thickness, different from the SOI, The cost of the SOI microplates and thin microplates is approximately 4 times that of the normal microplates. Therefore, it is desirable to use normal chips, to preserve the control of the geometry provided by the SOI and thin microplates. The processing of the normal thickness chips described in the following does not apply to the mordentad devices on both sides of the type described above. The processing of the chips other than the SOI, of normal thickness includes a step of grinding and a mechanical, chemical polishing. Figure 17 illustrates a basic process flow. Figure 18 illustrates an alternative process flow with an additional step. The additional step is an oxidation that aids in the mechanical chemical polishing process by providing a stop for chemical attack. Having a cap for chemical attack improves the uniformity of probe shapes. A third process flow is shown in Figure 19. This process flow has an additional step of a temporary joining to a flat, normal chip. The purpose of the joint is to rigidly fix the probes during the grinding and polishing steps. There is a possibility that during the grinding and polishing steps that the probes can not be kept sufficiently narrow using only adhesives and that a stronger bond may be necessary, such as that supplied by an oxide-to-oxide fusion bond. Otherwise, if the probes were moved during the grinding and polishing steps, they could decrease their sharpness. The standard chip used for temporary fusion bonding must be capable of being reused many times. Therefore, no significant costs are added, EXAMPLE IX As shown in Figure 17 (a), as the initial microplate 110, a monocrystalline silicon p-chip (100) of approximately 500 μ thickness is used. The chip is cleaned (step A) and about 0.5 μ of silicon nitride is deposited (step D). The deposited silicon nitride 112 is shown in Figure 17 (b). Silicon nitride is used as a masking material for the isotropic chemical attack of silicon. Then the silicon nitride is molded (step H), the chemical attack is carried out (step L) and the protective matter is removed (step K), producing the device of Figure 17 (c). The microplate is then immersed in a reagent for silicon isotropic attack (step 0) producing the device of Figure 17 (d). The microplate is then immersed in HF (step S) to remove the silicon nitride, giving rise to the device of Figure 17 (e). then the microplate is rinsed in deionized water for about 15 minutes. Most of the silicon chip is then rectified some microns from the bottom of the etched region. Then, using mechanical chemical polishing, the bottom of the chip is polished until the sharp structures are formed. The final device is shown in Figure 17 (f).

EXAMPLE X As shown in Figure 18 (a), a p-type monocrystalline silicon chip (100) of approximately 500 μ thickness is used as the starting material 110. The chip is cleaned (step A) and about 0.5 μ of silicon nitride is deposited (step D). The deposited silicon nitride 112 is shown in Figure 18 (b). Silicon nitride is used as a masking material for the isotropic chemical attack of silicon. The silicon nitride is then molded (step H), the chemical attack is performed (step L), and the protective matter is removed (step K) producing the device of Figure 18 (c). The microplate is then immersed in a reagent for isotropic silicon etching (step 0), producing the device of Figure 18 (d). The microplate is then immersed in HF (step S) to remove the silicon nitride, giving rise to the device of Figure 18 (e). The chip is then cleaned (step A) and the thermal growth of a 1 μ thick layer of SiO2 is carried out (step Y). The oxide layer 114 is shown in Figure 18 (f). Most of the silicon wafer is then rectified to some microns from the bottom of the etched region. Then, using mechanical chemical polishing, the lower part of the microplate is polished until the sharp structures are formed. The resulting device is shown in Figure 18 (g). The microplate is then immersed in HF (step S) to remove the oxide. Finally, the microplate is rinsed in deionized water for approximately 15 minutes, giving rise to the device of Figure 18 (h).

EXAMPLE XI As shown in Figure 19 (a) as the starting material 110, a monocrystalline silicon p-chip (100) of approximately 500 μ thickness is used. The chip is cleaned (step B) and about 0.5 μ of silicon nitride is deposited (step D). The deposited silicon nitride 112 is shown in Figure 19 (b). Silicon nitride is used as a masking material for isotropic silicon attack. The silicon nitride is then molded (step H), the chemical attack is performed (step L), and the protective matter is removed (step K), producing the device of Figure 19 (c). The microplate is then immersed in a reagent for isotropic silicon etching (step 0), producing the device of Figure 19 (d). The microplate is then immersed in HF (step S) to remove the silicon nitride, giving rise to the device of Figure 19 (e). The chip is then cleaned (step A) and the thermal growth of a 1 μ thick layer of SiO2 is carried out (step Y). The oxide layer 114 is shown in Figure 19 (f). In this point, the thermally oxidized chip 110 is joined (step Z) to a flat, normal, thermally oxidized chip having a layer of about 1 μ thickness of thermally developed SiO 2 therein (step Y). Figure 19 (g) illustrates the chip 110 attached to a grip chip 120, which has the oxide layer 122. The microsheet 110 is then ground to some microns of the bottom of the etched region. Then the chip is polished chemically and mechanically until the sharp structures are formed. The resulting device is shown in Figure 19 (h). Then the microchip is immersed in HF (step S) to eliminate the rust and the micro-grip plate. The chip is then rinsed in deionized water for approximately 15 minutes, giving rise to the device of Figure 1 (i).

EXAMPLE XII In one embodiment of the invention, the shape of the tip is controlled by adjustments in the conditions of the deposit of a phosphosilicate glass layer, which is sandwiched between the silicon nitride masking layer and the SOI device layer. . By incorporating a phosphosilicate glass layer between the masking layer and the monocrystalline silicon, the geometry of the tip can be controlled by changing the phosphorus doping of the phosphosilicate glass. It is possible to use phosphosilicate glass to prevent unwanted formation of hook at the tip. Figure 20 (a) illustrates a SOI 90 chip including an insulating layer 92 sandwiched between a chip 94 of the device and a grip chip 96. The device 94 is formed of monocrystalline silicon with a thickness of about 100 μ. The orientation is (100) or (110). The insulator is Si02 thermally developed, which is 1 to 2 μ thick, but can also be silicon nitride and / or chemically deposited oxide. The handle chip 96 is monocrystalline silicon of 500 μ of thickness with an orientation (100). Approximately 800 nanometers of phosphosilicate glass is deposited (step E) on the chip. Figure 20 (b) illustrates the phosphosilicate glass layer 130. Low-voltage silicon nitride is then deposited on the chip (step B). Figure 20 (c) illustrates the deposited layer 132. The silicon nitride layer 132 is then molded (step H). Next, the chemical attack of the silicon nitride layer is carried out (step L) and the chemical attack of the phosphosilicate glass layer is carried out (step J). This gives rise to the device of Figure 20 (d). The wet silicon attack is then performed (step O), producing the device of Figure 20 (e). Finally, the release with HF is performed (step S) [sic] producing the released device shown in Figure 20 (f). PSG reduces the incidence of hook formation at the tips. The problem of hooks at the tips occurs when the chemical attack mask to form the low voltage silicon nitride probe is deposited directly on the silicon. PSG placed between silicon nitride and silicon attacks faster than silicon [sic]. The material that attacks faster erodes during the etching process and therefore solves the problem of silicon hook formation. The attack speed of the PSG was measured for a variety of phosphine flow rates. The attack velocity results for PSG chips that have PH3 flow rates of 0.0, 1.2, 2.4, 3.6 and 4.8 sccm are shown in Figure 21. Also shown in Figure 21 is a horizontal line at 1100 Á / min which was the attack speed found for monocrystalline silicon. Based on the measured attack speeds, the PSG is a highly desirable material to correct the problem of hook formation, since its ratio of the attack speed to silicon can be designed from 0.1 to plus or minus 4.3. Figures 22A and 22B illustrate probes 140 and 141 constructed in accordance with any of the exemplary processes described herein. The probes do not include a channel and therefore are considered lancets or blades. The probes can be connected to larger structures to facilitate their use as lancets or blades. Probe 140 of Figure 22A has an isotropically etched tip formed on one side of the device, while probe 141 of Figure 22B has an etched tip isotropically formed on both sides of the device. Figure 23 illustrates a matrix of isotropically etched tips constructed in accordance with one embodiment of the invention. The matrix 150 is formed on a semiconductor substrate 152. More specifically, the matrix 150 is formed on a flat surface of the substrate 152. The device 150 can be used as a "raiser". That is to say, the device can be used to scrape the epidermis to facilitate the transdermal supply of the drug. Figure 24 is an amplified view of isotropically etched individual tips 154 of the matrix 150. The tips have common heights from 20 μ to 350 μ. The minimum separation between the points is determined by their height. The common separations are between twice the height at plus or minus 10 times the height. All points are manufactured using normal microplates. Three processes are described in the following. The first process gives rise to devices with sharp points. In some cases these sharp points may break during use due to the small cut at the tips. Hence, two other processes are included to form arrangements that have dull points that are more durable. The first alternative process is performed simply by prematurely interrupting the isotropic attack. The resulting structures have a flat top rather than a point. The second alternative process is performed by adding a PSG layer between the masking layer of the silicon nitride. The resulting structures have a pyramid-like shape.

EXAMPLE XIII As shown in Figure 25 (a), a monocrystalline silicon wafer (100) of approximately 500 μ thickness is used as the initial microplate 110. The chip is cleaned (step B) and about 0.5 μ of silicon nitride is deposited (step D). The deposited silicon nitride 112 is shown in Figure 25 (b). Silicon nitride is used as a masking material for isotropic silicon attack. Then the silicon nitride is molded (step H), the chemical attack is performed (step L), and the protective matter is removed (step K), producing the device of Figure 25 (c). The microplate is then immersed in a reagent for isotropic silicon etching (step O) until the sharp points are formed, as shown in Figure 25 (d). The microplate is then rinsed in deionized water for approximately 15 minutes. Next, the microplate is immersed in HF (step S) to remove the silicon nitride. Finally, the microplate is rinsed in deionized water for approximately 15 minutes, producing the device shown in Figure 25 (e).

EXAMPLE XIV As shown in Figure 26 (a), a monocrystalline silicon wafer (100) of approximately 500 μ thickness is used as the initial chip 110. The chip is cleaned (step B) and about 0.5 μ of silicon nitride is deposited (step D). The deposited silicon nitride 112 is shown in Figure 26 (b). Silicon nitride is used as a masking material for the isotropic attack of silicon. The silicon nitride is then molded (step H), the chemical attack is performed (step L), and the protective matter is removed (step K), producing the device of Figure 26 (c). The microplate is then immersed in a reagent for isotropic silicon etching (step O) and subsequently removed before the sharp points are formed. This processing results in the device of Figure 26 (d).

The microplate is then rinsed in deionized water for approximately 15 minutes. Next, the microplate is immersed in HF (step S) to remove the silicon nitride. Finally, the microplate is rinsed in deionized water for approximately 15 minutes, producing the device shown in Figure 26 (e).

EXAMPLE XV As shown in Figure 27 (a), a monocrystalline silicon wafer (100) of approximately 500 μ thickness is used as the initial chip 110. The chip is cleaned (step A) and about 0.8 μ of phosphosilicate glass (PSG) is deposited (step E). The PSG is then densified (step G). Then 0.5 μ of silicon nitride is deposited (step D). The deposited silicon nitride 112 and PSG 130 are shown in Figure 27 (b). Silicon nitride is used as the masking material for the isotropic attack of silicon. The silicon nitride is then molded (step H). Next, the chemical attack of the silicon nitride and the oxide layer is carried out (step L), and the protective matter is removed (step K), producing the device of Figure 27 (c). The microplate is then immersed in a reagent for silicon isotropic attack (step O). This processing results in the device of Figure 27 (b).

Then, the microplate is immersed in HF (step S) to remove the silicon nitride and PSG. Finally, the microplate is rinsed in deionized water for approximately 15 minutes, producing the device shown in Figure 27 (e). All the aforementioned examples share the common characteristic that they give rise to a device with an isotropically etched tip. The advantage of the probes described on the normal stainless steel probes is that they can be processed with smaller cross sections, sharper tips and can include integrated or micromachined circuit structures. Small cross sections and sharper tips give rise to a minimum of pain and tissue damage and integrated circuits provide a convenient means to incorporate screening operations, stimulation, pumping and valvulaje. Unlike the probes of the prior art, the probes of the present invention are constructed without doping with expensive boron. In addition, the processing does not require the use of ethylenediamine pirocatech carcinogen dangerous. Multiple variations to the process have been described to give rise to a variety of cross sections of the shaft. In addition, various styles of substrates have been described, including thinner-than-normal silicon wafers, silicon-on-insulator, and normal-thickness silicon wafers. However, all variations of the probes retain the high acuity of the tip, desired, which results from the isotropic attack. Although monocrystalline silicon is the preferred manufacturing material, it is possible to use other materials including, but not limited to, stainless steel, aluminum and titanium. Usually, these materials are not used in their monocrystalline form, so they can not be used in process flows that depend on highly anisotropic properties. The silicon probes of the invention may be coated with nickel, titanium, gold or similar metals that are sprayed or plated to improve the strength or surface characteristics of the probes. An organic coating, such as Parylene, can also be used to improve strength. The probes of the invention can also be thermally oxidized to improve their strength or surface characteristics. Other variations of the process include the use of an inductively coupled plasma attack to make the vertical side walls of the probe, as shown in Figures 6 and 7. The aforementioned description, for purposes of explanation, uses the specific nomenclature to provide a complete understanding of the invention. However, it will be apparent to those skilled in the art that specific details are not necessary for the practice of the invention. In other cases, well-known circuits and devices are shown in block diagram form to avoid unnecessary distraction of the underlying invention. Thus, the aforementioned descriptions of the specific embodiments of the present invention are presented for purposes of illustration and description. These are not intended to be exhaustive or to limit the invention to the precise forms described, of course many modifications and variations are possible in view of the above teachings. The modalities were chosen and described to better explain the principles of the invention and their practical applications, thereby enabling other experts in the art to better utilize the invention and the various embodiments with various modifications as are suitable for the particular use contemplated. It is proposed that the scope of the invention be defined by the following claims and their equivalents.

Claims (25)

1. A probe, comprising: an elongated leather with: an upper surface, a lower surface, a first side wall between the upper surface and the lower surface, a second side wall between the upper surface and the lower surface, and an end defined by the bottom surface converging at one point, an isotropically etched portion of the first side wall converging at the tip, and an isotropically etched portion of the second side wall converging at the tip.

2. The apparatus of claim 1, wherein the elongated body is less than about 700 μ in width.

3. The apparatus of claim 1, wherein the elongated body is less than about 200 μ in width.

4. The apparatus of claim 1, wherein the elongate body is formed of silicon.

The apparatus of claim 4, wherein the elongated body is formed of monocrystalline silicon.

The apparatus of claim 5, wherein the elongate body includes a polycrystalline silicon channel cap.

The apparatus of claim 4, wherein the elongate body is formed of silicon that is not contaminated with boron.

8. The apparatus of claim 1, wherein the elongate body includes integrated circuits.

9. The apparatus of claim 1, wherein the elongated body includes a micromachined structure.

The apparatus of claim 6, wherein the elongated body has a fluid channel formed therein.

11. A method of manufacturing a probe, the method comprising the steps of: providing an elongated body with an upper surface, a second lower surface and a series of side walls between the upper surface and the lower surface; and performing the isotropic attack on one end of the elongate body so that the bottom surface converges at one point and the series of side walls converges at the tip.

The method of claim 11, wherein the step of providing includes the step of providing an elongate body formed of silicon that is not doped with boron.

The method of claim 11, wherein the step of providing includes the step of providing an elongate body formed from a silicon chip on an insulator.

The method of claim 11, wherein the step of providing includes the step of providing an elongate body that is less than about 200 μ in thickness and less than about 700 μ in width.

The method of claim 11, wherein the step of providing includes the step of providing a phosphosilicate glass layer on the upper surface to control the attack velocity during the etching step and thereby prevent the formation of structures of hooks adjacent to the tip.

The method of claim 11, wherein the etching step includes the step of etching without ethylenediamine pyrocatechol. ,

17. The method of claim 11, wherein the etching step includes the step of processing the end exclusively at temperatures less than about 110 ° C.

18. The method of claim 11, wherein the etching step includes etching step with an anisotropic reagent.

19. The method of claim 11 further comprises the step of forming a channel for fluids within the elongated body.

20. The method of claim 11 further comprises the step of constructing integrated circuits on the elongated body.

21. The method of claim 11 further comprises the step of constructing a micromachined structure in the elongated body.

22. A method of manufacturing a device for epidermal abrasion, the method comprising the steps of: providing a semiconductor substrate with a flat surface; and performing the isotropic attack of the planar surface to form a matrix of structures isotropically etched on the semiconductor substrate.

23. The method of claim 22, wherein the etching step includes the step of forming a matrix of isotropically sharpened tips etched onto the semiconductor substrate.

The method of claim 22, wherein the etching step includes the step of forming a matrix of isotropically etched planar tips on the semiconductor substrate.

25. The method of claim 22, wherein the etching step includes the step of forming a matrix of isotropically etched pyramids on the semiconductor substrate.