JP2001101968A - Silicon lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon lens which can improve the positioning precision of silicon electrodes and reduce an electronic beam aberration. SOLUTION: A silicon electrode of a diaphragm structure 1, 5 consists of a thinner film 3, 7 formed around a thicker film forming a square shaped opening produced according to crystal direction. The thinner films 3, 7 have a circular opening 2, 6. The silicon electrodes 1 and 5 are assembled with their crystal faces 111} contacting each other through an insulation film 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon lens, and more particularly, to miniaturizing an electrostatic lens constituting a micro electron optical system using a micro cold cathode (emitter) or another cathode as a micro electron gun. For the combination structure for.

[0002]

2. Description of the Related Art In a micro electron gun using a micro cold cathode produced by a semiconductor process as an electron source, a small aperture-shaped electrode for accelerating or decelerating electrons emitted from an emitter or cutting out electrons, The lens electrode constituting the small electron beam optical system is manufactured using a semiconductor process or a micromachining process.

When these electrode parts are manufactured by using a semiconductor fine processing technique, the thickness of the electrodes is at most several tens μm.
And it is difficult to handle as a single item. On the other hand, when the machining technique is used, it becomes too large, and it is difficult to process and assemble an electrode having a thickness of 1 mm or less.

As one of means for solving these problems, there has been proposed a method of forming a silicon electrode by using anisotropic wet etching or anisotropic dry etching utilizing the crystal orientation of silicon. Therefore, a description will be given with reference to FIG.

FIG. 18 (a) to FIG. 18 (c) FIG. 18 (a) is a top view of a silicon electrode, and FIG.
FIG. 18B is a sectional view taken along a dashed line connecting AA ′ in FIG. 18A, and FIG. 18C is a bottom view.
First, a minute circular opening is formed at the center by performing anisotropic dry etching on one surface of the silicon substrate, and then wet etching is performed by using the crystal orientation from the opposite surface. The first silicon electrode 110 is formed by forming a rectangular opening 112 having a 111 ° plane as a side surface until reaching the bottom of the circular opening and making the circular opening a circular through opening 111.

In this case, the peripheral portion of the first silicon electrode 110 is a thick film portion 1 using the thickness of the silicon substrate as it is.
14, the periphery of the circular through-opening portion 111 has a diaphragm shape composed of a very thin thin film portion 113, and a silicon lens is formed by combining the two silicon electrodes thus manufactured. Therefore, an example of this silicon lens will be described with reference to FIG.

FIG. 19 (a) to FIG. 19 (c) FIG. 19 (a) is a top view of a silicon electrode, and FIG.
FIG. 19B is a cross-sectional view taken along a dashed line connecting AA ′ in FIG. 19A, and FIG. 19C is a bottom view.
As shown in the figure, two silicon electrodes, that is, a first silicon electrode 110 and a second silicon electrode 120 are joined using a glass 130 to form a two-stage silicon lens, By applying a predetermined voltage to each of the first silicon electrode 110 and the second silicon electrode 120 constituting the silicon lens to control the shape of the equipotential lines, the deflection of a charged particle beam such as an electron is controlled. Will be.

[0008]

However, as the dimensions of the electron gun and the optical system become smaller, the relative positional accuracy of each electrode constituting the lens is required, and it is more important to align the axis with the trajectory through which electrons pass. However, there is a problem in that the alignment of the individually completed silicon electrodes using some kind of alignment device is too expensive or insufficient in accuracy.

Further, a method of performing alignment using an optical fiber and a V-shaped groove of silicon has been proposed. However, processing accuracy of the optical fiber is required, an assembling method thereof is troublesome, and There is a problem in that it is difficult to bring the electrodes close to each other, and there are restrictions on the dimensions.

Further, as shown in FIG. 19, when a silicon electrode having a diaphragm shape manufactured by utilizing the crystal orientation of silicon is superposed, there is a problem that an adverse effect such as generation of aberration on an electron beam is caused. . This is because the rectangular openings 112 and 122 formed on one surface of the silicon electrode by anisotropic wet etching form an uneven electric field with respect to the electron orbit.

Accordingly, an object of the present invention is to improve the alignment accuracy of a silicon electrode and reduce the aberration of an electron beam of a silicon lens.

[0012]

FIG. 1 is an explanatory view of the principle configuration of the present invention. Referring to FIG. 1, means for solving the problems in the present invention will be described. FIG.
FIG. 1A is a cross-sectional view of a silicon lens, and FIG. 1B is an enlarged view enlarging the inside of a broken line circle in FIG. 1 (a) and 1 (b) (1) In the present invention, a thin film portion 3, 7 having a diaphragm structure composed of the thin film portions 3, 7 and a thick film portion around the thin film portions 3, 7 is formed by a rectangular opening utilizing a crystal orientation. In a silicon lens constituted by combining a plurality of silicon electrodes 1 and 5 provided with through openings 2 and 6, at least one pair of silicon electrodes 1 and 5 are provided.
5 are characterized in that their {111} surfaces are in contact with each other via an insulating film 9.

As described above, the positioning can be automatically performed by nesting and fitting using the {111} surfaces of each other, so that the positioning accuracy can be greatly improved, and In addition, the positioning process can be simplified. The {111} plane means a plane other than the (111) plane, which is crystallographically equivalent to the (111) plane such as the (1-11) plane and the (11-1) plane. The exponent that is originally displayed as "1 bar" for convenience of creation is "-
1 ".

At least one pair of silicon electrodes 1
By nesting 5, the distance between the silicon electrodes 1 and 5 can be made closer to the thickness of the silicon electrodes 1 and 5, and thereby, the non-uniformity of the electric field on the electron beam trajectory due to the square aperture Can be alleviated.

(2) The present invention provides the method according to (1), wherein the silicon electrodes 1 and 5 are three or more and have a relatively large square opening by using a square opening. The silicon electrodes 5 having a relatively small rectangular opening are nested so that the size of the rectangular opening is alternately increased from the inside to the outside in the vertical direction, and the nesting is incorporated inside. It is characterized in that at least one notch is provided in the thick film portion 4 formed around the silicon electrode 1 having a large square opening.

In this way, three or more lenses can be easily constructed by nesting them so that the size of the square openings increases in order from the inside to the outside and alternately increases vertically. , Each silicon electrode 1,
5, the control conditions for the voltage applied to 5 can be relaxed.
In this case, in order to apply a voltage to the inner silicon electrode 5, at least one thick film portion 4 formed around the silicon electrode 1 having a relatively large rectangular opening with a nest inserted therein is formed. It is necessary to provide two notches.

(3) Further, according to the present invention, in the above (1), the silicon electrodes 1 and 5 are three or more, and the silicon electrodes 1 having a relatively large square opening are formed by using a square opening. Thus, the silicon electrodes 5 having relatively small rectangular openings are nested so as to be sequentially arranged in the order of the size of the rectangular openings.

As described above, the silicon electrodes 5 having relatively small rectangular openings are nested so as to be sequentially arranged in the order of the size of the rectangular openings.
Three or more lenses can be miniaturized.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A manufacturing process of a first embodiment of the present invention in which a silicon lens is formed by combining two silicon electrodes will be described with reference to FIGS. First, the manufacturing process of the first silicon electrode will be described with reference to FIGS. Each drawing is a schematic cross-sectional view showing a manufacturing process when a silicon wafer is formed into a rectangular chip shape. Referring to FIG. 2A, first, the main surface is the (100) surface, and the thickness is, for example, 500 μm.
m is heat-treated in an oxidizing atmosphere, so that the entire surface of the silicon wafer 11 has a thickness of
For example, after a 500 nm thermal oxide film 12 is formed, a circular opening 14 is formed at the center by a photolithography process.
Is formed.

Referring to FIG. 2B, the thermal oxide film 12, ie, the SiO ₂ film is etched by anisotropic etching by reactive ion etching (RIE) using the resist pattern 13 as a mask, and the circular opening 15 is formed. To form

Next, after the resist pattern 13 is removed, the thermal oxide film 12 provided with the circular opening 15 is used as a mask to remove the resist pattern 13 again.
A circular opening 16 having a depth of 20 to 30 μm is formed by performing anisotropic etching by IE.

Next, as shown in FIG. 2D, the circular opening 1 is thermally oxidized again.
A thermal oxide film 17 is formed so as to cover 6.

Referring to FIG. 3E, a surface opposite to the surface on which the circular opening 16 is formed is
A resist pattern 18 having a square opening 19 at the center is formed by a photolithography process. In addition,
This square opening 19 is formed by a circular opening 16 formed on the surface.
It is formed using a double-sided mask aligner so that relative positioning can be performed.

Referring to FIG. 3F, RIE is performed using the resist pattern 18 as a mask.
Thermal oxide film 1 by anisotropic etching
7 is etched to form a square opening 20.

Next, after the resist pattern 18 is removed, anisotropic etching is performed using EPW which is a mixed solution of ethylenediamine and catechol, using the thermal oxide film 17 having the square openings 20 as a mask. Then, when the etching reaches the circular opening 16, the etching is stopped to form a square opening 21 and a circular through opening 22.

In this case, the EPW is the value of
The etching rate for the {1} plane is significantly lower than the etching rate for the {100} plane, and the etching proceeds while leaving the {111} plane.
All the sides of {11} are crystallographically equivalent to {111} planes.
It is composed of 1｝ plane.

Next, referring to FIG. 3H, the thermal oxide film 17 formed on the surface,
The first silicon electrode is completed by removing the iO ₂ film using hydrofluoric acid (HF).

FIGS. 4A to 4C are explanatory views of the structure of the first silicon electrode manufactured as described above. FIG. 4A is a top view and FIG. )
4A is a cross-sectional view taken along a dashed line connecting AA ′ in FIG. 4A, and FIG. 4C is a bottom view. As shown in the figure, the first silicon electrode 10 has a circular through opening 22 at the center for allowing an electron beam to pass therethrough, and a region near the center on the lower surface side is a square surrounded by a {111} plane. The thin film portion 23 formed by the opening 21 has a diaphragm shape, and around the thin film portion 23, a film thickness portion 24 for supporting the diaphragm portion is provided.

The manufacturing method shown in FIG. 2 and FIG.
This is a process in which one silicon electrode is formed on the chip-shaped silicon wafer 11 by using the chip-shaped silicon wafer 11, but usually, a plurality of silicon electrodes are formed on a large silicon wafer at once. Such a normal manufacturing process, that is, another manufacturing process of the first silicon electrode will be described with reference to FIG. FIG. 5A is a bottom view corresponding to FIG. 4C, and FIG.
It is sectional drawing along the dashed-dotted line which connects AA 'in (a).

5 (a) and 5 (b) A thermal oxide film (not shown) covering the front and back surfaces of the silicon wafer 11 in substantially the same manner up to the step of FIG. 2 (d).
Is formed, a square frame-shaped resist pattern 18 centered on a circular opening (not shown) is provided on the surface opposite to the surface provided with the circular opening, that is, on the lower surface side. Using the resist pattern 18 as a mask, the thermal oxide film is etched by anisotropic etching by RIE to form a square opening (not shown).

Next, after the resist pattern 18 is removed, the thermal oxide film provided with the square openings is used as a mask for the EP.
By performing anisotropic etching using W and stopping the etching when reaching the circular opening, a square opening 21 and a circular through opening 22 are formed. In the drawings, for the sake of simplicity, the rectangular opening 21 and the circular through-opening 22 are formed with the resist pattern 18 remaining for the sake of convenience.

In this case, an inclined side wall composed of a {111} plane is also formed outside the frame-shaped resist pattern 18, but is cut out along a dicing line indicated by a broken line in the figure to obtain the silicon shown in FIG. A silicon electrode having the same shape as the electrode is obtained.

Next, with reference to FIG. 6, a description will be given of a manufacturing process of the second silicon electrode according to the first embodiment of the present invention.
Note that this case is a manufacturing process for forming a plurality of silicon electrodes on a large silicon wafer, as in FIG. 5, and only one electrode is shown in the figure. Referring to FIG. 6A, first, the main surface is a (100) surface, and the thickness is, for example, 300 μm.
m is heat-treated in an oxidizing atmosphere, so that the entire surface of the silicon wafer 31 has a thickness of
For example, after forming a 500 nm thermal oxide film (not shown), a resist pattern 32 having a circular opening 33 at the center is formed by a photolithography process.

Referring to FIG. 6B, the thermal oxide film is etched by anisotropic etching by RIE using the resist pattern 32 as a mask to form a circular opening (not shown).
The resist pattern 32 is removed, and then anisotropic etching is performed again by RIE using the thermal oxide film provided with the circular opening as a mask to obtain a depth of 20 to 30 μm.
Is formed. Also in this case, for convenience, the circular opening 34 is illustrated with the resist pattern 32 remaining.

Next, as shown in FIG. 6C, the circular opening 3 is again oxidized by heat.
After a thermal oxide film (not shown) is formed so as to cover the entire surface of the rectangular opening 3, a square opening 3 in the center is formed on the surface opposite to the surface on which the circular opening 34 is formed by a photolithography process.
A resist pattern 35 having 6 is formed. The rectangular opening 36 is formed using a double-sided mask aligner so that the rectangular opening 36 can be relatively positioned with respect to the circular opening 34 formed on the surface.

Next, RIE is performed using the resist pattern 35 as a mask.
After the thermal oxide film is etched by anisotropic etching to form a square opening (not shown), the resist pattern 35 is removed, and then the EPW is formed using the thermal oxide film provided with the square opening as a mask. The anisotropic etching is performed using, and the etching is stopped when the circular opening 34 is reached.
And a circular through opening 38 is formed. Also in this case, for the sake of simplicity, the illustration shows that the rectangular opening 37 and the circular through-opening 38 are formed with the resist pattern 35 remaining for the sake of convenience. Also,
All side surfaces of the rectangular opening 37 are constituted by {111} planes which are crystallographically equivalent to the (111) plane.

Referring to FIG. 6E, the thermal oxide film formed on the surface is removed using hydrofluoric acid (HF), and then cut out along the dicing line shown by the broken line in FIG. 6D. Thereby, the second silicon electrode 30 having the thin film portion 39 at the center and the thick film portion 40 at the periphery is completed.

FIGS. 7A to 7C are explanatory views of the structure of the second silicon electrode manufactured as described above. FIG. 7A is a top view and FIG. )
7A is a cross-sectional view taken along a dashed line connecting AA ′ in FIG. 7A, and FIG. 7C is a bottom view, in which the upper and lower surfaces of the first silicon electrode 10 are reversed. ing. As shown in the figure, the second silicon electrode 30 has a circular through-opening 38 at the center for passing an electron beam, and a rectangular area surrounded by a {111} plane in a region near the center on the upper surface side. A structure in which a thin film portion 39 formed by the opening portion 37 forms a diaphragm, and a film thickness portion 40 for supporting the diaphragm portion having inner and outer walls formed of {111} surfaces is provided around the thin film portion 39. It has become.

Next, a method for bonding the first silicon electrode and the second silicon electrode according to the first embodiment of the present invention will be described with reference to FIG. 8A, first, the first silicon electrode 10 is thermally oxidized to form a thermal oxide film 25 having a thickness of, for example, 500 nm on the surface.
To form

Referring to FIG. 8B, an opening 26 is formed by etching the thermal oxide film 25 using hydrofluoric acid using a resist pattern (not shown) as a mask, and then the first silicon electrode 1 is formed.
The square openings 21 of the zero and the square openings 37 of the second silicon electrode 30 are nested so as to face each other. In this case, the {111} plane forming the square opening 21 of the first silicon electrode 10 and the {111} plane forming the outer wall of the thick film part of the second silicon electrode 30 come into contact with each other. The alignment is performed in a self-aligned manner, and a special alignment device or the like is not required.

Next, the first silicon electrode 10 and the first silicon electrode 10 are connected together so that the second silicon electrode 30 side is positive and the thermal oxide film 25 side, that is, the first silicon electrode 10 side, is negative. 2 silicon electrode 30 to heater 28
For example, in a state heated to 300 ° C., anodic bonding is performed by applying a voltage of, for example, 400 V by the DC power supply 27.

Next, by removing the exposed portion of the thermal oxide film 25 using hydrofluoric acid, an Einzel-type silicon lens combining two silicon electrodes is completed. In this case, the first silicon electrode 10 and the second silicon electrode 3
0 is electrically separated by the remaining thermal oxide film 25, and any voltage can be applied.

In the first embodiment of the present invention, since the two silicon electrodes are combined using the {111} planes forming the side walls of the film thickness portions, the two electrodes are aligned in a self-aligned manner. And the positioning of the circular through-opening portions 22 and 38 provided at the center can be accurately performed.

In addition, since the square openings 21 and 37 are nested so as to face each other when they are combined, the distance between the silicon electrodes can be reduced to be greater than the thickness of the silicon electrodes. Thereby, the non-uniformity of the electric field caused by the square openings 21 and 37 can be reduced, and thus a uniform axially required electric field distribution with respect to the electron beam trajectory can be formed.

Next, a second embodiment of the present invention in which a silicon lens is constituted by three silicon electrodes will be described with reference to FIGS. 9 to 12. In the drawings, the shape of the resist pattern is emphasized. Therefore, the illustration of the SiO ₂ film serving as a mask when etching the silicon wafer is omitted, and the resist pattern is left in a state where the silicon wafer is etched for convenience. First, with reference to FIG. 9, a description will be given of a manufacturing process of a medium-sized silicon electrode used in the second embodiment of the present invention. Note that FIG.
9A is a cross-sectional view, FIG. 9B is a bottom view, and FIG. 9C is a cross-sectional view taken along a dashed line connecting AA ′ in FIG. 9A.

Referring to FIG. 9A, first, the main surface is the (100) plane, and the thickness is, for example, 500 μm.
m is heat-treated in an oxidizing atmosphere so that the entire surface of the silicon wafer 51 has a thickness of
For example, after a thermal oxide film (not shown) of 500 nm is formed, a square resist pattern 52 having a circular opening 53 at the center is formed by a photolithography process.

Next, the thermal oxide film is etched by anisotropic etching by RIE using the resist pattern 52 as a mask to form a circular opening (not shown), and then the resist pattern 52 is removed.
Again using the thermal oxide film provided with the circular opening as a mask, RI
Anisotropic etching with E gives a depth of 2
A circular opening 54 of 0 to 30 μm is formed. At this time, a step 55 having the same depth as the circular opening 54 is also provided in the peripheral portion.
Is formed.

9 (b) and 9 (c). Then, the circular opening 5 is again thermally oxidized.
After forming a thermal oxide film (not shown) so as to cover the step 4 and the step portion 55, a square opening is formed at the center portion by a photolithography process on the surface opposite to the surface on which the circular opening 54 is formed. Then, a resist pattern 56 having a shape in which the center of one side is opened is formed.

Next, using the resist pattern 56 as a mask, the thermal oxide film is etched by anisotropic etching by RIE to form a partially opened rectangular opening (not shown).
6 and then anisotropically etching using EPW using a thermal oxide film provided with a partially opened rectangular opening as a mask to form a circular opening 54 and a peripheral step 55.
By stopping the etching at the time when the number of holes reaches the predetermined value, a square opening 57, a circular through opening 58, and a notch 59 are formed.

Next, the thermal oxide film formed on the surface is removed using hydrofluoric acid (HF) to complete the medium-sized silicon electrode 50. Also in this case, the inner and outer side walls of the thick film portion are formed of {111} planes.

Next, with reference to FIG. 10, a description will be given of a manufacturing process of the small silicon electrode used in the second embodiment of the present invention. FIG. 10A is a top view, and FIG.
10B is a cross-sectional view taken along a dashed line connecting AA ′ in FIG. 10A, FIG. 10C is a bottom view, and FIG. 10D is FIG. 10C. FIG. 3 is a sectional view taken along a dashed line connecting BB ′ in FIG.

Referring to FIGS. 10A and 10B, first, the main surface is the (100) surface, and the thickness is, for example, 300 μm.
m, by heat-treating the silicon wafer 61 in an oxidizing atmosphere,
For example, after forming a thermal oxide film (not shown) of 500 nm, a resist pattern 62 composed of a square pattern having a circular opening 63 at the center and a protruding pattern is formed by a photolithography process.

Next, the thermal oxide film is etched by anisotropic etching by RIE using the resist pattern 62 as a mask to form a circular opening (not shown), and then the resist pattern 62 is removed.
Again using the thermal oxide film provided with the circular opening as a mask, RI
Anisotropic etching with E gives a depth of 2
A circular opening 64 of 0 to 30 μm is formed. At this time, a step portion having the same depth as the circular opening 64 is also formed in the peripheral portion.

Next, referring to FIGS. 10C and 10D, the circular opening 6 is again thermally oxidized.
Thermal oxide film (not shown) to cover step 4 and step
After the formation of the resist pattern, a resist pattern having a rectangular opening in the center by a photolithography process and a projection corresponding to the projection of the resist pattern 62 is formed on the surface opposite to the surface on which the circular opening 64 is formed. Form 65.

Then, using the resist pattern 65 as a mask, the thermal oxide film is etched by anisotropic etching by RIE to form a square opening (not shown).
After the formation of the resist pattern 65, the resist pattern 65 is removed.
By performing anisotropic etching using W and stopping the etching when reaching the circular opening 64 and the peripheral step, the square opening 66, the circular through opening 67,
And, the protrusion 68 is formed.

Next, the small-sized silicon electrode 60 is completed by removing the thermal oxide film formed on the surface using hydrofluoric acid (HF). Also in this case, the inner and outer side walls of the thick film portion and the protruding portion 68 are constituted by {111} planes, and the thick film protruding portion 68 becomes an electrode lead portion of the small silicon electrode 60.

Next, the manufacturing process of the large silicon electrode used in the second embodiment of the present invention will be described with reference to FIG. 11. The manufacturing process is shown in FIG. 9, although the size is slightly different. Substantially the same as the medium silicon electrode. In addition,
11 (a) is a top view, and FIGS. 11 (b) and 11 (c) are cross sections taken along a dashed line connecting AA 'and BB' in FIG. 11 (a), respectively. FIG.

Referring to FIGS. 11A to 11C, first, as in the case of FIG. 9A, a silicon wafer 71 having a (100) main surface and a thickness of, for example, 500 μm is placed in an oxidizing atmosphere. After forming a thermal oxide film (not shown) having a thickness of, for example, 500 nm on the entire surface of the silicon wafer 71 by a heat treatment, a square resist pattern having a circular opening at the center by a photolithography process. (Not shown), and then anisotropically etching by RIE using this resist pattern as a mask to etch the thermal oxide film,
After a circular opening (not shown) is formed, the resist pattern is removed, and then anisotropic etching is performed again by RIE using the thermal oxide film provided with the circular opening as a mask to obtain a 20 to 30 μm deep. A circular opening (not shown) is formed. At this time, a step portion having the same depth as the circular opening is also formed in the peripheral portion.

Then, again by thermal oxidation,
After a thermal oxide film (not shown) is formed so as to cover the circular opening and the stepped portion, the surface opposite to the surface on which the circular opening is formed, that is, the upper surface is formed by photolithography at the center. A resist pattern 72 having a rectangular opening and having a central portion opened on one side is formed.

Next, using the resist pattern 72 as a mask, the thermal oxide film is etched by anisotropic etching by RIE to form a partially opened rectangular opening (not shown).
2 is anisotropically etched using an EPW using a thermal oxide film provided with a partially opened rectangular opening as a mask, and etched when the circular opening and the peripheral step are reached. Are stopped to form a square opening 73, a circular through opening 74, and a cutout 75.

Next, the thermal oxide film formed on the surface is removed using hydrofluoric acid (HF) to complete the large silicon electrode 70. Also in this case, the inner and outer side walls of the thick film portion are formed of {111} planes.

Next, a silicon lens having the structure shown in FIG. 12 is manufactured by performing the anodic bonding method shown in FIG. 8 twice. FIG. 12A is a top view, and FIGS. 12B and 12C are FIGS.
It is sectional drawing which follows the dashed-dotted line which connects AA 'and BB' in (a). 12 (a) to 12 (c) That is, similarly to the case shown in FIG. 8, first, the medium-sized silicon electrode 50 is thermally oxidized so that, for example,
After forming a thermal oxide film (not shown) having a thickness of 500 nm, an opening is formed by etching the thermal oxide film using hydrofluoric acid using a resist pattern (not shown) as a mask.

Next, the square opening 57 of the middle silicon electrode 50 and the square opening 66 of the small silicon electrode 60 face each other, and the cutout 59 provided in the middle silicon electrode 50 and the small silicon electrode 60 are provided. The projections 68 are nested so that the projections 68 correspond to each other. In this case, the {111} plane forming the square opening 57 of the middle-sized silicon electrode 50 and the {111} plane forming the outer wall of the thick film part of the small silicon electrode 60 are in contact with each other and are self-aligned. Since positioning is performed, a special positioning device or the like is not required.

Next, the small silicon electrode 60 and the medium silicon electrode 50 are heated at, for example, 300.degree.
In this state, the anodic bonding is performed by applying a voltage of, for example, 400 V by a DC power source so that the small silicon electrode 60 side is positive and the middle silicon electrode 50 side is negative.

Next, the square opening 57 of the medium-sized silicon electrode 50 in which the small-sized silicon electrodes 60 are nested is formed.
And the rectangular opening 73 of the large silicon electrode 70 are opposed to each other, and the cutout 75 provided on the large silicon electrode 70 and the projection 68 provided on the small silicon electrode 60 are nested so as to correspond to each other. . In this case, the outer wall of the thick film portion of the middle silicon electrode 50 is formed.
Since the {1} plane and the {111} plane constituting the square opening 73 of the large silicon electrode 70 are in contact with each other and are aligned in a self-aligned manner, a special alignment device or the like is not required.

Next, the large silicon electrode 70 and the medium silicon electrode 50 are heated at 350 ° C. by a heater, for example.
In this state, the anode is bonded by applying a voltage of, for example, 400 V by a DC power supply so that the large silicon electrode 60 side is positive and the medium silicon electrode 50 side is negative.

Next, the exposed portion of the thermal oxide film is removed by using hydrofluoric acid to complete an Einzel-type silicon lens combining three silicon electrodes. In this case as well, between the middle silicon electrode 50 and the small silicon electrode 60 and between the middle silicon electrode 50 and the large silicon electrode 70 are electrically separated by the remaining thermal oxide film (not shown). Therefore, an arbitrary voltage can be applied to each silicon electrode.

Also in the second embodiment of the present invention, since the three silicon electrodes are combined using the {111} planes forming the side walls of the film thickness portions, the alignment is performed in a self-aligned manner. And the positioning of the circular through-openings 58, 67, 74 provided at the center can be performed accurately.

Further, when combining, the rectangular openings are nested so that the sizes of the rectangular openings are alternately increased vertically from inside to outside so that the rectangular openings face each other. The distance between them can be made closer than the thickness of the silicon electrode, thereby reducing the non-uniformity of the electric field caused by the square openings 57, 66, 73, so that the It is possible to form a required axially symmetric and uniform electric field distribution. Also, since the distance between the electrodes is relatively wide,
This limits the applied voltage.

Next, a third embodiment of the present invention will be described with reference to FIGS. 13 to 16. In the manufacturing process of a small silicon electrode and a large silicon electrode, a projection and a notch are provided. However, since the substantial steps are the same as those of the above-described second embodiment, the description of the manufacturing steps of the small silicon electrode and the large silicon electrode will be omitted. First, FIG.
With reference to FIG. 3, an overall configuration of a silicon lens according to a third embodiment of the present invention will be described. FIG. 13A is a top view, and FIG.
FIG. 1 is a sectional view taken along a dashed line connecting A ′, and FIG.
FIG. 3C is an enlarged view of the inside of the dashed circle in FIG.

Referring to FIGS. 13 (a) and 13 (b), as in the case shown in FIG.
After thermally oxidizing 4 to form a thermal oxide film (not shown) having a thickness of, for example, 500 nm on the surface, the thermal oxide film is formed using hydrofluoric acid with a resist pattern (not shown) as a mask. An opening is formed by etching.

Next, the square openings 86 of the middle silicon electrode 84 and the square openings 83 of the small silicon electrode 81 are nested so as to face each other. In this case, the {111} plane forming the square opening 86 of the middle-sized silicon electrode 84 and the {111} plane forming the outer wall of the thick film part of the small silicon electrode 81 contact each other and are self-aligned. Since positioning is performed, a special positioning device or the like is not required.

Next, the small silicon electrode 81 and the medium silicon electrode 84 are heated at, for example, 300 ° C.
In this state, the anodic bonding is performed by applying a voltage of, for example, 400 V by a DC power supply so that the small silicon electrode 81 side is positive and the medium silicon electrode 84 side is negative.

Next, the circular through opening 8 of the middle silicon electrode 84 in which the small silicon electrodes 81 are nested is formed.
5 are nested so that the square openings 89 of the large silicon electrodes 87 face each other. In this case, {111} forming the outer wall of the thick film portion of the middle silicon electrode 84 is formed.
The surface and the {111} surface forming the rectangular opening 89 of the large silicon electrode 87 are in contact with each other to perform alignment in a self-aligning manner, so that a special alignment device or the like is not required.

Next, the large silicon electrode 87 and the medium silicon electrode 84 are heated at 350 ° C. by a heater, for example.
In this state, the anode is bonded by applying a voltage of, for example, 400 V by a DC power source so that the large silicon electrode 87 side is positive and the medium silicon electrode 84 side is negative. Next, by removing the exposed portion of the thermal oxide film using hydrofluoric acid, an Einzel-type silicon lens combining three silicon electrodes is completed.

Referring to FIG. 13C, also in this case, the thermal oxide films 90 and 91 remain between the middle silicon electrode 84 and the small silicon electrode 81 and between the middle silicon electrode 84 and the large silicon electrode 87. Since it is electrically isolated, any voltage can be applied to each silicon electrode.

In the third embodiment, since the shape of the outer wall of the thick film portion of the middle silicon electrode 84 is different from that of the second embodiment, the third embodiment will be described with reference to FIGS.
The manufacturing process and structure of the medium-sized silicon electrode according to the embodiment will be described. First, the manufacturing process of the medium-sized silicon electrode will be described with reference to FIGS. Each drawing is a schematic cross-sectional view showing a manufacturing process when a silicon wafer is formed into a rectangular chip shape. Referring to FIG. 14A, first, the main surface is the (100) plane, and the thickness is, for example, 500 μm.
m is heat-treated in an oxidizing atmosphere so that the entire surface of the silicon wafer 92 has a thickness of
For example, after a 500 nm thermal oxide film 93 is formed, a circular opening 95 is formed at the center by a photolithography process.
Is formed, and then the thermal oxide film 93 is etched by anisotropic etching by RIE using the resist pattern 94 as a mask to form a circular opening 96.

Next, after the resist pattern 94 is removed, the thermal oxide film 93 provided with the circular opening 96 is used as a mask to remove the resist pattern 94 again.
By performing anisotropic etching by IE, a circular opening 97 having a depth of 20 to 30 μm is formed.

Next, as shown in FIG. 14C, the circular opening 9 is formed by thermal oxidation again.
A thermal oxide film 98 is formed so as to cover 7.

Next, as shown in FIG. 14D, a resist pattern 99 having a shape exposing a rectangular frame around the surface on which the circular opening 97 is formed is formed.
By performing anisotropic etching by RIE using the resist pattern 99 as a mask, an exposed portion around the thermal oxide film 98 is etched. The resist pattern 99 is provided so as to cover the entire surface opposite to the surface on which the circular opening 97 is formed.

Next, after the resist pattern 99 is removed, anisotropic etching is performed using EPW with the thermal oxide film 98 as a mask, thereby crystallographically equivalent to the (111) plane. A side wall made of a {111} plane is formed.

Next, as shown in FIG. 15F, the exposed # 1 was thermally oxidized again.
Thermal oxide film 10 so as to cover the side wall composed of the 11 ° plane.
0 is formed.

Next, as shown in FIG. 15G, a surface opposite to the surface on which the circular opening 97 is formed is
After forming a resist pattern 101 having a square opening 102 at the center by a photolithography process, the thermal oxide film 10 is anisotropically etched by RIE using the resist pattern 101 as a mask.
0 is etched to form a square opening 103. In this case, the rectangular opening 102 is formed using a double-sided mask aligner so that the rectangular opening 102 can be relatively aligned with the circular opening 97 formed on the surface.

Next, after removing the resist pattern 101, the thermal oxide film 100 provided with the square openings 103 is used as a mask, as shown in FIG.
Anisotropic etching is performed using EPW, and a circular opening 9 is formed.
By stopping the etching when it reaches 7,
A square opening 86 and a circular through opening 85 are formed.
Also in this case, all side surfaces of the square opening 86 are (11)
1) It is composed of {111} plane which is crystallographically equivalent to the plane.

Referring to FIG. 15I, the thermal oxide film 101 formed on the surface is removed using hydrofluoric acid to complete the middle silicon electrode 84.

FIGS. 16A to 16C are explanatory views of the structure of the medium-sized silicon electrode manufactured as described above. FIG. 16A is a bottom view, and FIG.
FIG. 16B is a cross-sectional view taken along a dashed line connecting AA ′ in FIG. 16A, and FIG. 16C is a top view. As shown in the figure, the middle-sized silicon electrode 84 has a circular through-opening 85 through which an electron beam passes in the center, and the side wall of the thick film around the rectangular opening 86 is inclined in the same inclination direction. It has a structure composed of 111 ° planes.

Also in the third embodiment of the present invention, since the three silicon electrodes are combined using the {111} planes forming the side walls of the film thickness portions, the alignment is performed in a self-aligned manner. Therefore, the positioning of the circular through-openings 82, 85, 88 provided at the center can be accurately performed.

When three silicon electrodes are combined, silicon electrodes having relatively small square openings are nested so as to be sequentially arranged in the order of the size of the square openings. Since the middle-sized silicon electrode 84 and the large-sized silicon electrode 87 are nested in this order, the distance between the silicon electrodes can be made shorter than in the above-described second embodiment. The size can be reduced, and the square openings 83, 86, 89 can be formed.
Can alleviate the non-uniformity of the electric field, so that it is possible to form a uniform axially symmetric electric field distribution required for the electron beam orbit.

Next, a fourth embodiment of the present invention will be described with reference to FIG. 17, except that the method of joining the small silicon electrode and the medium silicon electrode is different, and the other manufacturing steps and structures are the same as those described above. A detailed description of the third embodiment which is substantially the same as that of the third embodiment is omitted. FIG. 17A is a top view, FIG. 17B is a cross-sectional view taken along a dashed line connecting AA ′ in FIG. 17A, and FIG.
(C) is an enlarged view of the inside of the dashed circle in FIG. 17 (b).

Referring to FIGS. 17A and 17B, first, a medium-sized silicon electrode 8 is formed without forming a thermal oxide film.
4 and the rectangular opening 106 of the small silicon electrode 104 are nested so as to face each other, and they are joined using a direct joining method, that is, a diffusion joining method or a eutectic joining method. I do. In the case of using the eutectic bonding method, Al or Au is formed on the bonding surface of one silicon electrode, and then heated to a temperature at which Al or Au and silicon form a eutectic. There is no need for a voltage application device or the like that is legal.

After that, a thermal oxide film (not shown) having a thickness of, for example, 500 nm is formed on the surface by thermally oxidizing the large silicon electrode 97, and then using the resist pattern (not shown) as a mask. An opening is formed by etching the thermal oxide film using hydrofluoric acid.

Next, the small silicon electrode 104 is nested so that the circular through opening 85 of the middle silicon electrode 84 in which the small silicon electrode 104 is nested and the square opening 89 of the large silicon electrode 87 face each other. While the electrode 87 and the medium-sized silicon electrode 84 are heated to, for example, 350 ° C. by a heater, a voltage of, for example, 400 V is applied by a DC power supply so that the large-sized silicon electrode 87 is negative and the medium-sized silicon electrode 84 is positive. Anodic bonding. Next, by removing the exposed portion of the thermal oxide film using hydrofluoric acid, an Einzel-type silicon lens combining three silicon electrodes is completed.

Referring to FIG. 17C, in this case, the middle silicon electrode 84 and the large silicon electrode 8
7 are electrically separated by the remaining thermal oxide film 90, but the middle silicon electrode 84 and the small silicon electrode 81 are directly joined and electrically short-circuited. The result is a two-piece silicon lens.

In the fourth embodiment of the present invention, three silicon electrodes are used to form a two-piece silicon lens, but one electrode is composed of two silicon electrodes, that is, a small electrode 104 and a medium silicon Since it is constituted by the electrode 84, the exposed portion to the outside is constituted by a flat surface having the same electric potential electrically. Therefore, the square opening 106 of the small silicon electrode 104 and the square opening 86 of the medium silicon electrode 84 are formed. Does not affect the electric field distribution,
It is possible to form a more uniform electric field distribution.

The embodiments of the present invention have been described above.
However, the present invention is limited to the configuration described in each embodiment.
Instead, various changes are possible. For example, on
In the description of each of the embodiments, the {111} plane is formed.
EPW is used as an anisotropic etchant for
But not limited to EPW, potassium hydroxide
A solution (KOH) may be used. In addition, use KOH
In such a case, SiO 2 is used as a protective film._TwoSi instead of film_ThreeN
_FourIt is necessary to use a membrane.

Although the above embodiments do not refer to the impurity concentration or the specific resistance of a silicon wafer for forming a silicon electrode, for example, an n-type silicon substrate having a specific resistance of 1 Ω · cm is used. Silicon may be used.

When an n-type silicon wafer is used, a p-type layer having a thickness of 20 to 30 μm may be previously formed on the side where the circular opening is provided in order to easily detect the etching end point. Things.

In the first embodiment, the surface of the first silicon electrode is thermally oxidized, and the first silicon electrode side is biased so as to be negative and anodic bonding is performed. The surface of the second silicon electrode may be thermally oxidized. In any case, the bias may be applied so that the silicon electrode side on which the thermal oxide film is formed becomes negative.

In the second to fourth embodiments, the outer wall surface of the thick film portion of the large silicon electrode also has
Although the plane is constituted by the 1 plane, the plane is not necessarily required to be the {111} plane, and may be a vertical plane by dicing as shown in the manufacturing method in FIG.

In each of the above embodiments, the silicon lens is constituted by a set of two or three lenses.
It may be constituted by a set of four or more. In the case of assembling as in the second embodiment, at least two or more silicon electrodes to be incorporated inside are provided with protrusions constituting electrode lead portions. Must be provided.

[0101]

According to the present invention, the electron beam provided on each silicon electrode is nested using the {111} plane formed by utilizing the etching anisotropy of the silicon single crystal. The self-aligning positioning of the circular through-opening, which is the passage opening of the silicon electrode, and the distance between the silicon electrodes can be made closer, thereby reducing the non-uniformity of the electric field on the electron beam orbit. It is possible to reduce the aberration of the electron beam by alleviating it, thereby greatly contributing to higher performance or lower cost of the silicon lens.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a basic configuration of the present invention.

FIG. 2 is an explanatory diagram of a manufacturing process partway through the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a manufacturing process of the first embodiment of the present invention up to the middle of FIG. 2;

FIG. 4 is an explanatory diagram of a structure of a first silicon electrode.

FIG. 5 is an explanatory diagram of another manufacturing process of the first silicon electrode.

FIG. 6 is an explanatory view of a manufacturing process of the first embodiment of the present invention up to the middle of FIG. 3;

FIG. 7 is an explanatory diagram of a structure of a second silicon electrode.

FIG. 8 is an explanatory view of a manufacturing process of the first embodiment of the present invention up to the middle of FIG. 6;

FIG. 9 is an explanatory diagram of a manufacturing process partway through a second embodiment of the present invention.

FIG. 10 is an explanatory view of the manufacturing process of the second embodiment of the present invention up to the middle of FIG. 9;

FIG. 11 is an explanatory diagram of a manufacturing process of the second embodiment of the present invention up to the middle of FIG. 10;

FIG. 12 is an explanatory view of the manufacturing process of the second embodiment of the present invention after FIG. 11;

FIG. 13 is an explanatory diagram of a third embodiment of the present invention.

FIG. 14 is an explanatory diagram of a manufacturing process of a middle-sized silicon electrode according to the third embodiment of the present invention halfway;

FIG. 15 is an explanatory diagram of a manufacturing process of the middle-sized silicon electrode according to the third embodiment of the present invention after FIG. 14;

FIG. 16 is an explanatory diagram of a structure of a medium-sized silicon electrode according to the third embodiment of this invention.

FIG. 17 is an explanatory diagram of a fourth embodiment of the present invention.

FIG. 18 is an explanatory view of a structure of a conventional silicon electrode.

FIG. 19 is an explanatory diagram of a structure of a conventional silicon lens.

[Explanation of symbols]

 Reference Signs List 1 silicon electrode 2 circular through opening 3 thin film part 4 thick film part 5 silicon electrode 6 circular through opening 7 thin film part 8 thick film part 9 insulating film 10 first silicon electrode 11 silicon wafer 12 thermal oxide film 13 resist pattern 14 circular opening Reference Signs List 15 circular opening 16 circular opening 17 thermal oxide film 18 resist pattern 19 square opening 20 square opening 21 square opening 22 circular through opening 23 thin film portion 24 thick film portion 25 thermal oxide film 26 opening 27 DC power supply 28 heater 30 second Silicon electrode 31 silicon wafer 32 resist pattern 33 circular opening 34 circular opening 35 resist pattern 36 square opening 37 square opening 38 circular through opening 39 thin film part 40 thick film part 50 medium silicon electrode 51 silicon wafer 52 resist pattern 53 circular opening 5 Circular opening 55 Stepped portion 56 Resist pattern 57 Square opening 58 Circular through opening 59 Notch 60 Small silicon electrode 61 Silicon wafer 62 Resist pattern 63 Circular opening 64 Circular opening 65 Resist pattern 66 Square opening 67 Circular through opening Part 68 Projecting part 70 Large silicon electrode 71 Silicon wafer 72 Resist pattern 73 Square opening 74 Circular through opening 75 Notch 81 Small silicon electrode 82 Circular through opening 83 Square opening 84 Medium silicon electrode 85 Circular through opening 86 Square opening 87 Large silicon electrode 88 Circular through opening 89 Square opening 90 Thermal oxide film 91 Thermal oxide film 92 Silicon wafer 93 Thermal oxide film 94 Resist pattern 95 Circular opening 96 Circular opening 97 Circular opening 98 thermal oxide film 99 resist pattern 100 thermal oxide film 101 resist pattern 102 square opening 103 square opening 104 small silicon electrode 105 circular through opening 106 square opening 110 first silicon electrode 111 circular through opening 112 square opening 113 thin film Part 114 Thick film part 120 Second silicon electrode 121 Circular through opening 122 Square opening 130 Glass

Claims (3)

[Claims] 1. A silicon structure comprising a combination of a plurality of silicon electrodes in which a circular through opening is provided in a thin film portion of a diaphragm structure comprising a thin film portion and a thick film portion around the thin film portion by a rectangular opening utilizing a crystal orientation. In the lens,
A silicon lens, characterized in that at least one pair of silicon electrodes is in contact with each other on {111} surfaces via an insulating film. 2. The method according to claim 1, wherein the silicon electrode comprises three or more electrodes,
Utilizing the rectangular opening, a silicon electrode having a relatively small rectangular opening is alternately arranged with a silicon electrode having a relatively small rectangular opening from the inner side to the outer side. It is characterized in that at least one cutout portion is provided in a thick film portion formed around a silicon electrode having a relatively large square opening with a nest incorporated therein while being nested so as to become larger. The silicon lens according to claim 1. 3. The method according to claim 2, wherein the silicon electrode comprises three or more electrodes,
Utilizing the square opening, a silicon electrode having a relatively small square opening is nested with a silicon electrode having a relatively small square opening so as to be sequentially arranged in the order of the size of the square opening. The silicon lens according to claim 1, wherein: