JPH0762978B2 - Method for manufacturing sharp microtips for scanning probe microscopy - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for manufacturing a sharp microtip for a scanning probe microscope, and more particularly,
A method of manufacturing a sharp microtip for a scanning probe microscope cast in a mold.

[0002]

2. Description of the Related Art Micro chips have been applied in many fields in science and technology such as sensors, actuators, vacuum micro electronic devices, microfluidics and microscope usage. Microchips are also used to converge the flow at a single point or as a mechanical probe. Generally, it is difficult to manufacture such a microchip in a reproducible manner at all times. This is because very sharp tip edges are important for reliable operation of microchips in many situations.

Marcus's article "The Oxidation of Shaped Silicon Surfaces" discussing how a sharp silicon knife blade can be made (Journal of the Electrochemic
al Society, Solid-state Science and Technology, 19
June 1982, pages 1,278 to 1,282). There are several publications in the art that provide some background information on the manufacture of microchips. One of them is Stephani's paper "Fabrication of Densely Packed Sharp Silicon Fiel".
d Emitters Using Dry Etching Techniques ”(manufacturing dense packed pointed silicon field emitters using dry etching technology)” (distributed at the second international conference on vacuum microelectronics held in July 1989). Another paper, Marcus's paper "Formation of Silicon Tip"
s with <1 nm Radius (formation of silicon chip with radius less than 1 nm) ”(" Applied Physics Letter ", Vol.
56, No. 3, January 15, 1990, Nos. 236-238.
Page).

In particular, a scanning tunneling microscope (scanning t
Scanning probe microscopes and atomic force microscopes such as unnering microscopes (STMs)
s, AFMs) requires a sharp tip. The end of a typical scanning probe microscope is in contact with or placed close to the surface to be imaged. Not only should the tip be sharp, it is most desirable to have a surface contour that facilitates scanning. As far as the sharpness is concerned, it is desired that the tip end radius of the tip incorporated in the STM (scanning tunneling microscope) or the AFM (atomic force microscope) is 500 angstroms or less. That is, it is desired that the tip of the scanning probe microscope is terminated with a single atom. With respect to the surface contour of the chip, it is important for high resolution that the rest of the chip does not interfere with proper positioning of the edge of the chip.

There are various types of microfabrication processes as a method of making chips by casting in an off-the-shelf silicon mold. One method is "Microcasting of Microminiature T
It is disclosed in U.S. Pat. No. 4,916,002 entitled "ips (ultra-precision casting of ultra-small chips)". This method starts by forming pyramidal pits (recesses) in a silicon wafer by anisotropic etching of silicon. Next, the pits are filled with a chip material such as silicon nitride or metal. Then, the wafer is bonded to the second substrate and the original substrate forming the mold is selectively etched until the chips are exposed. In this type of method, the final surface contour and sharpness of the resulting chip is
Initially determined by the mold surface contour and sharpness. One drawback of this method is that the contour and sharpness of the mold are unreliable, and the other drawback is that if the pits cause some form error due to natural process vibrations in the manufacturing environment, the blades instead of the cusps. A chip is formed that terminates at the end, which adversely affects the resolution obtained by the chip.

The microchip is also attached to the end of the member forming the cantilever. One way to make such a cantilever is "Microminiatu
It is disclosed in U.S. Pat. No. 4,943,719 entitled "re Cantilever Stylus". This method includes a step of forming a rectangular silicon post in (100) silicon and a step of etching the top of the silicon post to leave a silicon chip at a corner of the remaining part of the silicon post. Thereafter, silicon dioxide cantilevers with integral tips are thermally grown on silicon wafers and sharpened silicon tips. One drawback of this method is that the narrow profile provided on the resulting chip cannot be in the form of a concave surface profile.

Applicant has another pending US patent application relating to a method for sharpening off-the-shelf silicon chips. This patent application was filed on October 10, 1989 and is assigned the application number 07 / 418,663. This patent application teaches only the method of sharpening tips made of silicon, not the method of sharpening tips made of other materials. Also, this patent application does not teach or suggest how to form a chip with desired sharp edges and surface contours from the beginning, but how to improve an off-the-shelf silicon chip. Is just teaching.

[0008]

SUMMARY OF THE INVENTION The object of the present invention was made in view of the above problems of the conventional sharp microminiature tip, and the sharp microminiature tip for a scanning probe microscope having high reproducibility. It aims at providing the manufacturing method of.

Another object of the present invention is to provide a method for manufacturing a microchip for a highly reliable scanning probe microscope, which comprises a cantilever terminating in a microchip provided with a free end. To aim.

[0010]

The first invention of the present application that achieves the above object is a method of manufacturing a microchip for a scanning probe microscope by casting in a mold, and a step of forming a cavity of the method. 850 in a step of forming a cavity in the single crystal silicon substrate to form a mold cavity having a female shape that is substantially the same as the shape desired for the microchip after 850.
Exposing the silicon to oxidizing species at a temperature in the range of 1000 ° C. to 1000 ° C. to form a layer of silicon dioxide shaped to form a sharp edge on the microchip to form a recessed mold cavity. And depositing a chip material in the cavity to cast the shape of the sharp end formed by the layer of silicon dioxide into the microchip. A method for manufacturing a sharp microtip for a scanning probe microscope.

The second invention of the present application is also a method of manufacturing a microchip for a scanning probe microscope having a cantilever terminating in a microchip provided with a free end, wherein a predetermined surface of a single crystal silicon substrate is provided. The microchip after the steps of coating a layer of masking material, forming openings in the masking material to expose selected areas of the surface of the single crystal silicon substrate, and forming cavities of the method. Forming a cavity in the selected area of the wafer to form a mold cavity having a female shape approximately equal to the desired shape for
850 to 1000 in part of the cavity
Exposing the silicon to an oxidizing species selected from the group consisting of oxygen and water vapor at temperatures in the range of ° C;
Forming a layer of silicon dioxide in the microtip having a shape for forming a sharp edge to form a silicon / silicon dioxide recessed profile mold cavity. A method for manufacturing a sharp microminiature tip for a probe microscope.

The second invention further comprises depositing a layer of cantilever material on the substrate and depositing a tip material in the mold cavity to define the shape of the pointed tip formed by the layer of silicon dioxide. Casting a chip having a tip and forming a patterned coupling between the layer of cantilever material and the tip to form a cantilever with the tip.

[0013]

The accompanying drawings, which form a part of the invention, show an embodiment of the invention and together with a description of the embodiment the principle of the invention. Oxidation of silicon is oxygen,
It occurs when oxygen molecules of oxidizing species, such as steam or other water vapor, contact silicon molecules on the silicon surface. After the initial layer of silicon dioxide (SiO ₂ ) is formed, further oxidation only occurs if additional oxidizing molecules diffuse through the existing layer of silicon dioxide. The additional oxidizing molecules must diffuse to the interface between the layer of silicon dioxide and the silicon itself, forming part of the reaction with which oxygen combines with silicon. After the formation of hundreds of angstroms of initial silicon dioxide on the silicon surface, the growth rate of any additional silicon dioxide is primarily due to the diffusion of new oxide molecules through the existing layer of silicon dioxide and the formation of silicon dioxide. It is determined by the rate at which it reaches the interface with silicon dioxide. As the oxidation reaction progresses, the layer of silicon dioxide becomes so thick that no new silicon dioxide is actually formed with increasing temperature or increasing time.

Silicon dioxide formed on silicon at low temperatures of 850-1,000 ° C. is known to have higher compressive stresses (in the case of oxides) on the surface of corners than on flat surfaces. Also, the higher compressive stress in the oxide has the effect of suppressing the diffusivity of oxidizing species into the silicon, which reduces the rate of oxidation and therefore the oxidation on the corner surface compared to on a flat surface. It is believed that the thickness of the object will decrease. For example, RB Marcus and TT Sheng's paper "The Oxidation of Sharp Silicon Surfaces"("Journal of the Electro-Ch
emical Society ", June 1982, pp.1,278-1,282)
Please refer to.

FIG. 1 shows an array of silicon dioxide mold cavities for simultaneously producing multiple chips. This array is a silicon substrate 13 with cavities.
And each cavity has a female shape that is approximately equal to the shape desired for a microchip. The layer 12 of silicon dioxide is on the cavity wall 11 and on the silicon substrate 13.
Is grown on the top surface of. The layer 12 of silicon dioxide has different thicknesses that form a convex surface contour terminating in the sharp end 10. Therefore, microtips made from each of these molds have a concave surface contour and a sharp edge corresponding to the mold. An array of mold cavities consisting of silicon and silicon dioxide (referred to as "silicon / silicon dioxide mold cavities") can greatly increase chip productivity as it simultaneously manufactures multiple chips and / or cantilever chip assemblies, Suitable for mass production.

2-4 show the steps of forming a microchip using the conventional method of casting a chip in a single crystal silicon mold. The method starts by forming pyramidal pits in a (100) silicon substrate by anisotropic etching of silicon. FIG. 2 shows the silicon substrate 14 having the pits 16 formed therein. The pit 16 has relatively flat surfaces 17, 18 that converge at the end 19. Next, as shown in FIG. 3, the pit 16 is filled with the chip material 21. Next, the silicon substrate 14 is bonded to the second substrate 22. FIG. 4 shows a state in which the base portion 23 is bonded to the second substrate 22 and the chip 24 is exposed after the original silicon substrate 14 is selectively removed by etching. Further, in FIG. 4, the contours 26 and 27 of the side surfaces are flat, and the surface 1 of the silicon substrate 14 is
It is shown that the contours coincide with the contours of Nos. 7 and 18.

FIG. 5 shows a pyramidal tip 28 cast by a conventional silicon mold. The tip 28 has a square base 29 and relatively flat sides 31, 32 which, together with the other sides, terminate in a point 33. It is desirable to have a chip that terminates at a single point. FIG. 6 shows a tip 34 cast in a coarsely formed silicon mold. Such molds often occur in the manufacturing environment due to vibrations during the manufacturing process and cause the chip 3 to have relatively flat sides 37, 38.
4 is formed. These sides 37, 38, together with the other sides, terminate as a blade 39. Such a chip 34 is not preferable in an application requiring point contact.

7 to 10 show a process of forming a micro chip according to the present invention. The tip is cast, but has a sharpened free end as compared to prior art cast tips. The tip also has a preferred concave surface contour. Figure 7
The cavity 41 has a female shape that is approximately the same as the shape desired for a chip formed on a (100) single crystal silicon substrate 42. The cavity 41 is formed in a conventional manner, and one way to form the cavity 41 is to use anisotropic etching of silicon. Cavity 41, like conventional cavities, has relatively flat cavity walls 43, 44 that converge toward a cavity bottom 46. According to the invention,
Next, a layer 47 of silicon dioxide having a thickness of 500 to 10,000 angstroms is grown on the surface of the cavity 41. This layer 47 is formed with varying thicknesses so as to form a mold cavity with the desired shape suitable for chip casting. This is shown in FIG.

The layer 47 of silicon dioxide is formed by exposing the silicon (silicon substrate) 42 to oxidizing species such as oxygen or steam at temperatures in the range of 850 to 1,000 ° C. At the above low temperature, silicon is abnormally oxidized, so that the thickness of the silicon dioxide layer formed on both side surfaces 43 and 44 is equal to the thickness of the dioxide formed on the bottom portion 46 of the cavity and the portion close to the bottom portion 46. It is much thicker than the silicon layer. This thickness difference causes the contours of the surfaces 49, 51 of the silicon / silicon dioxide mold cavity 50 to be much more convex than the contours of the original silicon cavity surfaces (eg, surfaces 43, 44). . Both surfaces 49, 51 converge to form a sharpened edge 52. FIG. 9 shows a tip material 53, such as silicon dioxide or metal, deposited in the mold cavity 50 to cast a tip 54 with the shape of a sharpened tip 52. Next, the second piece 56 of the substrate 56 (which can be made of glass, metal or silicon) is bonded to the base 55 of the chip 54 to form a support for the chip 54. FIG. 10 shows a sharpened silicon chip obtained by selectively etching away the silicon substrate 42 and the layer 47 of silicon dioxide after the chip material 53 has hardened. As shown, the tip 54 has concave contoured surfaces (concave surface contours) 57, 58 that converge to form a sharpened end 59.

FIG. 11 shows a pyramidal tip 61 formed using the present invention. The tip 61 has a square base 62 on a substrate 56 and concave contoured sides 63, 64 which, together with the other sides, terminate at a point 66. The surface contour of the chip 61 is
As shown in FIGS. 7 and 8, a silicon pit (cavity) 41 formed before depositing the chip material 53.
A female contour equivalent to the surfaces 49, 61 of the upper layer 47 of silicon dioxide. It is desired that the tip 61 terminates at a point. FIG. 12 is a plan view of the pyramidal tip 61.

FIG. 13 shows a chip 67 formed using the present invention. The chip 67 includes a rectangular base 68 on the silicon substrate 42 and side surfaces 69, 7 having a concave contour.
1 and the side surfaces 69, 71 terminate in a somewhat concave alternative, namely the blade 72, with the other side surfaces. Blade-terminated tips allow for greater line contact and thus reduced contact impedance.
Such a chip is desirable in electrical equipment that requires low contact impedance and vacuum microelectronic equipment in which noise of emission current is reduced by adopting such a structure.

FIGS. 15 to 19 show a method of forming a microchip assembly in which a chip is cast in a mold and then a member for attaching to the chip is formed to form a cantilever. FIG. 15 shows a given surface of a single crystal silicon substrate 42 coated with a masking layer 73 made of a material such as silicon dioxide or metal. Next, an opening is formed in the masking layer 73 to expose a selected region on the surface of the silicon substrate 42. Next, the cavity 41 is formed on the silicon substrate 42 in the exposed region. The cavity 4
1 has a relatively flat cavity wall 43, 44 which converges towards the bottom 46. According to the present invention, next, in a portion having a shape capable of forming a sharp end portion on a chip as shown in FIG.
A layer 74 of silicon dioxide having a thickness of 0 to 10,000 Angstroms is grown on the cavity 41. The layer of silicon dioxide 74 is formed by exposing the silicon substrate 42 to oxidizing species such as oxygen or steam at temperatures in the range of 850-1,000 ° C. Due to the abnormal oxidation of silicon at low temperature, a thickness difference occurs in the layer of silicon dioxide, and the surface (wall) 43, 4
The layer of silicon dioxide formed on 4 is much thicker than the layer formed on the bottom 46 of the cavity.
This difference in thickness of the layers of silicon dioxide results in a silicon / silicone with contoured surfaces 77, 78 that are much more convex than the contours of the original silicon cavity surface (eg, surfaces 43, 44).
A silicon dioxide mold cavity 76 is formed in the silicon dioxide layer. The surfaces 77, 78 converge with the other surfaces to form a pointed end 79. Next, the mask layer (masking layer) 73 is removed. Next, as shown in FIG. 17, a chip material 80 is deposited in the mold cavity 76 to cast a chip 81 having a shape of a sharp end 79.
Tip material 80 is also deposited to form cantilevers 82. Alternatively, one pattern layer for the cantilevers can be deposited and other different materials can be deposited for the chips. However, the one-piece structure seems to be stronger.

FIG. 18 shows a free-standing cantilever 82 with a sharp tip 85 exposed after removing a portion of the silicon dioxide layer 74 and a selected portion of the silicon substrate 42. The tip 81 has concave contoured surfaces 83, 84 which converge to form a sharpened edge 85. FIG. 19 shows that while the support 86 was also attached to the layer of silicon dioxide 74 and the silicon substrate 42, the support 86
FIG. 4 illustrates another method of making a free-standing cantilever by joining (which can be made of glass, metal or silicon) to a cantilever. Next, the silicon substrate 42
And a layer of silicon dioxide 74 is removed to provide support 8 at one end.
6 forms a self-supporting cantilever with a sharpened end 81 at the other end.

FIG. 20 is a conceptual diagram of an atomic force microscope (AFM) which is one form of the scanning probe microscope. According to conventional practice, the scan obtained by AFM is similar to a raster scan. Scanning in the X and Y directions is performed by the X, Y, Z scanning stage 104. Sample 1
03 is supported by a pair of tubular piezoelectric scanners 106, 107 arranged between the immovable structure 108 and both ends of the sample.

Scanning is controlled by a programmed microcontroller or computer 111. Computer 111 also analyzes the measurement data and displays the measurement information on display 112. The surface of the sample is scanned using X, Y, Z transducers in some AFMs, moving the cantilever while keeping the sample stationary. In other AFMs, the cantilever is held stationary while the X, Y, Z transducer stages move the sample.

According to the present invention, the free end of the microminiature cantilever arm 101 is provided with a protruding tip 102 used for probing the surface of the sample 103. A body portion extends from the base of the tip 102, the body portion forming a pointed end with a concave contour terminating at a point along its length. The concave contour of the tip 102 gives the tip surface a narrow contour, making the tip surface suitable for access without contacting the walls of holes or other irregularities on the surface of the sample 103 to be scanned, and thus Improves scanning resolution.

The AFM of the present invention has a "contact mode" of operation.
And is the same as the conventional one in that it has a “non-contact mode”.
In the contact mode of operation, the chip 102 is 10 ^-5
It is mounted on the surface of the sample 103 with a very small tracking force on the order of ^{-10 -10} N. This results in very high resolution surface topography. The concave surface of the chip helps to obtain such high resolution. Images showing the positions of individual atoms on the surface of the sample can be constantly acquired. In the second operating mode or contactless mode, the chip 1
02 is held at a short distance (on the order of 5 to 500 angstroms) from the surface of the sample 103, and various forces (electrostatic force, magnetic force, van der Waals force, etc.) between the sample 103 and the chip 102 are used. To be bent. The surface shape of the tip of the tip helps localize atomic interactions. In either mode of operation, a measurement of the surface microstructure or other properties of the sample is obtained by measuring the deflection of the cantilever 101. The bending of the cantilever 101 is detected by the bending sensor 11 connected to the bending measuring circuit 114.
3 (typically using precisely aligned optics)
, But other techniques can be used.

Atomic force microscopy (AFM) is capable of imaging conductive and insulating surfaces using atomic resolution. A typical AFM has a displacement measurement sensitivity of 0.1 angstrom. Other types of scanning probe microscopes to which the present invention is applicable include scanning tunneling microscopes and near-field acoustic microscopes. Figure 21
Is a hole 125 formed in a structure 124 using a microchip 121 cast using a conventional silicon mold.
It is a state in which an attempt is made to reach the bottom surface of the. The flat profile of the side surface of the tip end 122 causes the side surface to contact the wall of the hole 125, and therefore the portion of the bottom surface 126 near the wall of the hole 125 cannot be scanned.

FIG. 22 shows a sharp microtip 127 cast using the present invention in the area on the bottom surface 126 of the same hole 125 as was not possible with a conventional silicon mold tip 121. It has reached the state.
The microchip formed in accordance with the present invention has a fairly narrow profile due to the concave surface profile, so that its sharpened tip end 128 also has a bottom surface 126 proximate to the wall of hole 125. It can be scanned without touching the wall.

The foregoing description of specific embodiments of the present invention has been presented for purposes of illustration and description only, and is not intended to limit the invention to the precise form set forth. Therefore, various modifications can be made based on the above disclosure. The embodiments described were chosen and described in order to best explain the principles and practical application of the invention, and those skilled in the art will therefore find that the invention is best suited to suit the particular application for which it is actually intended. Can be used and various changes can be made. The scope of the invention is limited by the claims and their equivalents.

[Brief description of drawings]

FIG. 1 is a perspective view showing a portion of an array of cavities in a silicon mold with a layer of silicon dioxide.

FIG. 2 is a cross-sectional view showing one step of a method of manufacturing a microchip using a conventional silicon mold.

FIG. 3 is a cross-sectional view showing one step of a method for manufacturing a microminiaturized chip using a conventional silicon mold.

FIG. 4 is a cross-sectional view showing one step of a method of manufacturing a microchip using a conventional silicon mold.

FIG. 5 is a perspective view showing a pyramidal tip terminating at a point.

FIG. 6 is a perspective view showing a pyramid-shaped tip terminating like a blade.

FIG. 7 is a cross-sectional view showing one step of a method of manufacturing a microchip from a silicon / silicon dioxide mold cavity according to the present invention.

FIG. 8 is a cross-sectional view illustrating one step of a method of manufacturing a microchip from a silicon / silicon dioxide mold cavity according to the present invention.

FIG. 9 is a cross-sectional view showing one step of a method of manufacturing a microchip from a silicon / silicon dioxide mold cavity according to the present invention.

FIG. 10 is a cross-sectional view showing one step of a method of manufacturing a microchip from a silicon / silicon dioxide mold cavity according to the present invention.

FIG. 11 is a perspective view showing a pyramidal tip terminated with a cusp manufactured according to the present invention.

FIG. 12 is a plan view showing a pyramidal tip terminating at a cusp manufactured according to the present invention.

FIG. 13 is a perspective view showing a pyramidal tip terminating in a blade manufactured according to the present invention.

FIG. 14 is a plan view showing a pyramidal tip terminating in a blade manufactured according to the present invention.

FIG. 15 is a cross-sectional view showing a processing step when manufacturing a chip assembly including a cantilever.

FIG. 16 is a cross-sectional view showing a processing step when manufacturing a chip assembly including a cantilever.

FIG. 17 is a cross-sectional view showing a processing step when manufacturing a chip assembly including a cantilever.

FIG. 18 is a cross-sectional view showing a processing step when manufacturing a chip assembly including a cantilever.

FIG. 19 is a cross-sectional view showing a processing step when manufacturing a chip assembly including a cantilever.

FIG. 20 is a block diagram showing a schematic configuration of an atomic force microscope.

FIG. 21 is a cross-sectional view showing a state in which the surface contour of a hole is scanned using a conventional microminiature chip.

FIG. 22 is a cross-sectional view showing a state in which the surface contour of a hole is scanned using the microchip according to the present invention.

[Explanation of symbols]

10 Sharp Edge 11 Cavity Wall 12 Silicon Dioxide Layer 13 Silicon Substrate 14 Silicon Substrate 16 Pit 17 Relatively Flat Surface 18 Relatively Flat Surface 19 Edge 21 Chip Material 22 Second Substrate 23 Base 24 Chip 26 Side Profile 27 Side Profile 28 Pyramidal Chip 29 Base 31 Relatively Flat Side 32 Relatively Flat Side 33 Spire 34 Chip 37 Relatively Flat Side 38 Relatively Flat Side 39 Blade 41 Cavity 42 Single Crystal Silicon Substrate 43 Comparison Flat cavity wall 44 relatively flat cavity wall 46 cavity bottom 47 silicon dioxide layer 49 silicon / silicon dioxide mold cavity surface 50 silicon / silicon dioxide mold cavity 51 silicon / silicon dioxide mold cavity surface 52 silicon / Silicon dioxide mold cavity sharp edge 53 Chip material 54 Chip 55 Chip base 56 Second piece of substrate 57 Concave contour surface 58 Concave contour surface 59 Sharp tip 61 Pyramidal tip 62 Square base 63 Concave contour Sides of concave 64 Sides of concave contour 66 Sharp points 67 Tips 68 Rectangular base 69 Surface of concave contour 71 Surface of concave contour 72 Blade (somewhat concave line) 73 Mask layer (masking layer) 74 Silicon dioxide Layer 77 Convex Contoured Surface 78 Convex Contoured Surface 79 Sharp Edge 80 Tip Material 81 Tip 82 Cantilever 83 Concave Contoured Surface 84 Concave Contoured Surface 85 Sharpened Tip 86 Support 101 Microminiature Cantilever Arm 102 Protruding Tip 103 Sample 104 X, Y, Z scanning stage 106 Tubular piezoelectric scanner 107 Tubular Piezoelectric scanner 108 Immovable structure 111 Microcontroller (computer) 112 Display 113 Deflection sensor 114 Deflection measurement circuit 121 Microminiature chip 122 cast using a conventional silicon mold 122 Tip end 124 Structure 125 hole 126 Bottom of hole 127 The present invention Micro chip 128 formed by

Claims (11)

[Claims] 1. A method of manufacturing a microtip for a scanning probe microscope by casting in a mold, comprising a female die having a shape substantially equal to a desired shape of the microtip after the step of forming the cavity of the method. Forming a cavity for forming a shaped mold cavity in the single crystal silicon substrate, and 850 to 1000 in a part of the cavity.
Exposing the silicon to oxidizing species at a temperature in the range of ° C to form a layer of silicon dioxide shaped to form sharp edges on the microchip to form a concave-shaped mold cavity. And a step of depositing a tip material in the cavity to cast the shape of the sharp end formed by the layer of silicon dioxide into the microchip. A method for manufacturing a sharp microchip for a microscope. 2. The method of claim 1, further comprising the step of joining a support to the microminiature chip after casting. 3. The method of claim 1, further comprising removing the silicon and silicon dioxide layers from the tip material to expose the sharp microtips after the tip material has hardened. The method described in. 4. The method of claim 1, wherein the oxidizing species is selected from the group consisting of oxygen and water vapor. 5. The step of forming a layer of silicon dioxide provides the layer with a thickness in the range of 500 to 10,000 angstroms and has a convex contour for forming a sharp edge on the microchip. The method of claim 1, wherein a mold cavity is formed. 6. The method of claim 1, wherein all cavity walls of the mold cavity converge toward the bottom of the mold cavity. 7. The step of forming the mold cavity comprises:
The method according to claim 1, comprising a step of anisotropically etching the single crystal silicon substrate. 8. A method for manufacturing a microchip for a scanning probe microscope having a cantilever terminating in a microchip provided with a free end, wherein a predetermined surface of a single crystal silicon substrate is coated with a layer of a masking material. The step of forming an opening in the masking material to expose a selected region of the surface of the single crystal silicon substrate, and the step of forming a cavity of the method, after the step of Forming cavities in the selected area of the wafer to form mold cavities of equal female shape, and 850 to 1000 in a portion of the cavities.
Exposing the silicon to an oxidizing species selected from the group consisting of oxygen and water vapor at temperatures in the range of ° C;
Forming a layer of silicon dioxide shaped to form a sharp edge on the microchip to form a silicon / silicon dioxide recessed profile mold cavity; depositing a layer of cantilever material on the substrate And depositing a tip material in the mold cavity to cast a tip having the shape of the pointed end formed by the layer of silicon dioxide and patterning between the layer of cantilever material and the tip. Forming a coupling and forming a cantilever having the tip, the method for producing a sharp microminiature tip for a scanning probe microscope. 9. The method of claim 8 further comprising the step of removing silicon and silicon dioxide to form a free-standing cantilever with a sharp microtip. 10. The method of claim 8 wherein all cavity walls of the cavity are concave contours that converge toward the bottom of the cavity. 11. At a temperature in the range of 850 to 1,000 ° C.,
Exposing the silicon to an oxidizing species selected from the group consisting of oxygen and steam; and forming a layer of the silicon dioxide to a thickness in the range of 500 to 10,000 Angstroms to form a pointed tip on the tip. Forming a silicon / silicon dioxide mold cavity having a contoured profile.