JPH0638411B2 - Pattern formation method by electron beam - Google Patents

Description

The present invention relates to a method for forming a desired pattern on a substrate by changing a substance by a synergistic effect of excited reactive particles and an electron beam.

Here, the excited reactive particles are, as described later, excited by microwaves at a position apart from the reaction chamber, and are composed of long-lived radicals that can be transported to the reaction chamber or short-lived reactive particles. It is a general term including reactively excited particles excited by a photochemically excited reaction in a broad sense including a wavelength electromagnetic light wave.

In the conventionally reported plasma etching, a pattern is formed by forming a resist pattern in advance and using it as a protective mask, and then performing a plasma reaction over the entire surface.

In addition, plasma oxidation for growing an oxide film on the surface of a semiconductor or a metal in a reduced-pressure oxygen discharge (oxygen plasma) can be formed at a low temperature, and thus has wide application potential.

In these processes, selective patterning was not possible without masking masking materials. Photochemical reactions have the effect of exciting gaseous molecules into reactively excited particles, but on the other hand, they have the characteristic that they can directly form a pattern by sending a reactive gas or reactively excited particles while irradiating a light pattern. There is. However, in many cases, it is inferior in fine workability as compared with pattern formation by an electron beam.

On the other hand, pattern formation by an electron beam is limited to a special substance such as a resist.

On the other hand, the reactive excitation particles in the plasma and the reactive excitation particles due to the photochemical reaction described above can directly process various substances such as etching and oxidation.

In view of the above situation, the present invention does not preliminarily install a resist pattern or a shielding pattern such as a SiO ₂ film on a substrate, imparts pattern information to the electron beam itself, and reacts with the electron beam on the substrate to excite particles. Change the substance due to the action with the atmosphere only in the selected place, and in the part where the electron beam is not irradiated, make such change only insignificantly, or rarely under the appropriately selected condition. The main purpose of this is to maintain the miniaturization of the pattern by the electron beam and to enable direct pattern formation.

An outline of the pattern formation method of the present invention will be described. An electron beam having an appropriately selected acceleration energy is used to form an electron optical film on a substrate in an atmosphere containing reactive excitation particles made possible by differential evacuation or the like. Select a reactive excitation particle that draws a two-dimensional pattern by imaging with a system and reasonably causes the reaction due to the synergistic effect of the reactive excitation particle and the electron beam on the substrate in the same elementary process. It can be summarized as a pattern formation method that can be mechanically processed. Hereinafter, the present invention will be described in detail based on examples.

FIG. 1 shows a substrate portion in a reaction chamber by imparting pattern information to the electron beam of the present invention and projecting the electron beam onto a substrate in an atmosphere containing reactive excitation particles through an electron optical system. FIG. 3 is a schematic configuration diagram of an apparatus capable of forming in a patterned state a change in a substance caused by an electron beam and an atmosphere of reactive excitation particles acting on a substrate substance in FIG. In FIG. 1 showing an embodiment of the present invention,
The electron optical system will be described from the top. An electron gun 1 for supplying electrons, a first diaphragm 2, an aligner 3, a first electromagnetic lens 4, a blanking plate 5, a second diaphragm 6, a second electromagnetic lens 7, and a third electromagnetic. A double deflection coil 8a and a stigmator 8b are arranged in the lens (objective lens) 9 and the third electromagnetic lens 9. An electron beam is incident on the reaction chamber through the third diaphragm 10. Since the required degree of vacuum differs greatly between the reaction chamber where the substrate is installed and the electron optical system, differential evacuation is performed by multiple evacuation systems, and reactive excitation particles etc. to the electron optical system are used. Contamination will be prevented and the vacuum required for electron beam scanning and control will be maintained.

The focused electron beam 11 is applied to the substrate 12 to draw a pattern. The board is installed on the board support base 13,
The support base is configured so that the temperature of the substrate part can be controlled by heating at a low temperature, if necessary.

The support base 13 is installed on the X-Y moving mechanisms 14 and 15, and can perform precision alignment and precision movement equivalent to those of a normal electron beam drawing apparatus. Various materials in the reaction chamber 16 are composed of materials that are not corroded by the atmosphere of reaction excited particles such as plasma.

In the embodiment shown in FIG. 1, each electron beam optical system has an exhaust port.
Differentially exhausted by 17, 18, and 19. Exhaust port of reaction chamber
Exhausted by 20. The pressure in the reaction chamber is determined by the exhaust capacity from these exhaust ports 19, 20 and the like. On the other hand, electric field excited plasma, which is one of the important elements among the reactive excitation particles, can be introduced through the transport tube 21. 2.45 GHz microwave generated by magnetron oscillation is introduced into the waveguide 22a in front of the transport tube,
A quartz tube reaction part 23 is inserted in a part of the waveguide. The end of the waveguide is impedance-matched by a matching device 22b. CF ₄ + O ₂ gas is introduced into the quartz tube through the inlet tube 23a at about 0.1 Torr. When introduced at a pressure of this level, the generated plasma hardly spreads even with an increase in electric power, becomes in a stable state, and the matching condition is not broken even with a change in gas flow rate. If the plasma transport tube 21 is coated with Teflon, the active species generated in the discharge part can be introduced into the reaction chamber 16 without being significantly attenuated even in the reaction chamber about 1 m away. That is, such active species are long-lived radicals.

Such a 2.45 GHz microwave-excited plasma etching method has been conventionally reported. According to this method, various thin films such as polycrystalline silicon SiN ₄ , SiO ₂ , Nb, W, Mo and photoresist are etched. The condition is the pressure of CF ₄ .
At 0.12 Torr, Pr = Po ₂ / PCF ₄ can be etched up to 0-4. The advantage of the plasma etching method based on this excitation method is that no electrode for discharge is required in the reaction chamber 16.

In the above plasma excitation method, O ₂ was used as an introduced gas.
Alternatively, plasma oxidation or nitridation with plasma-activated oxygen or nitrogen with N ₂ is also possible under certain conditions.

In the above description, the reactive excitation particles in the reaction chamber 16 are, as described above, so-called long plasma-excited so-called long plasma-excited particles that can reach the reaction chamber without being significantly attenuated even if they are generated at a distance of about 1 m. It is a life-time radical. However, the means capable of forming the reactive excitation particles in the reaction chamber 16 is not limited to the above-mentioned excitation method. Recently, there have been many reports of reactive gas particles caused by photoexcitation reactions such as infrared light, visible light, ultraviolet light, and deep UV light. Further, depending on the case, the gas phase particles can be excited by an electromagnetic light wave chemical reaction also by an electromagnetic light wave having a short wavelength from the deep UV light to the X-ray. Photochemical reaction processes include, for example, Si for Cl ₂ or B.
It is known that dry etching can be performed by optically exciting the gas of r ₂ with a laser beam of 4880Å or 2570Å. GaAs and InP can also be etched by the reaction of CH ₃ Br gas with deep UV excitation light. Proposed as one embodiment of the present invention, which also incorporates the effect of reactive gas particles by electromagnetic light wave photochemical reaction, the pattern formation method by electron beam drawing with pattern information is based on the findings of the reports of various reactions described above. There is.

In FIG. 1, a light beam 24 is a scannable light beam for exciting a photochemical reaction. The light flux 24L from the light source is from a light source for exciting a photochemical reaction from a laser or the like. A light flux control system 25 is arranged to switch the light flux 24L temporally or spatially change the direction, position, etc. of the light flux. The luminous flux 24M emitted from the luminous flux control system 25 is a reflecting mirror 26 and a reflecting mirror 27,
It becomes the light beam 24a that reaches the vicinity of the sample through the light beam transmitting window 28 and the plane or concave cylindrical reflecting mirror 29.

The gas for photochemical reaction is introduced into the reaction chamber 16 from the gas sources 31, 32 through the valve 30. The photochemical reaction gas undergoes photochemical excitation in the light passage space in the reaction chamber such as the position of the light beam 24b in the depressurized atmosphere.

Further, the light beam 24a directly irradiated to the vicinity of the sample surface or the sample surface acts more strongly on the photochemical reaction. In particular, when the sample surface is directly irradiated, local heating and activation due to photoexcitation of the sample surface, electron-hole excitation, and the like are added, so that a multi-element reaction mechanism is added. Further, the light flux 24a may have an annealing effect on the substrate.

Uniformity of light irradiation on the sample surface by making the light beam 24a scannable,
It is also possible to increase controllability. Mechanically, the mirrors 26, 27 and 29 may be driven by a fine movement control mechanism. Faster operation is possible by installing an electronic optical switch or optical path changing device in the light flux control system 25.

Further, if a switch, a half mirror, a microlens array, an optical fiber, or the like, which uses some polarized light, is used, a plurality of light beams can be processed simultaneously and in parallel. As a result, each of the plurality of light beams can be uniquely intermittently timed and spatially arranged.

The optical system including the light flux control system 25 and the mirrors 26, 27, 29 shown in FIG. 1 is one embodiment. It can be seen that various other light flux controls are possible. It is also possible to separately provide a plurality of light flux transmitting windows in the electron beam pattern writing system as shown in FIG. 1 and to make a plurality of light flux groups enter the respective light flux transmitting windows spatially and temporally intermittently. Alternatively, there is an advantage in that there is no difference in the control of the light flux between the vacuum and the atmosphere. Therefore, the various luminous flux group control systems described above are used in the reaction chamber.
It is also possible to go inside 16. It is possible to irradiate a plurality of light fluxes with a spatial distribution and a temporal discontinuity in a specific case within the substrate by making the above light flux groups enter obliquely in the vicinity of the substrate in the reaction chamber.

When installing the light flux control system in the reaction chamber, a quartz plate, so that the light flux control system is not damaged by the reactive excitation particles,
It is necessary to provide a storage container that can protect the material of Teflon coat.

As described in detail above, by utilizing the present invention, plasma treatment by microwave-excited long-lived radicals, photochemical treatment by photochemically reactive excited particles, and reactivity excited by these two types of excitation methods A fine pattern drawing function by an electron beam can be added to a process using excited particles together.

Further, according to the present invention, the portion hit by the electron beam is the other portion due to the reaction effect of the electron beam and the reactive excitation particles on the substrate, for example, local damage by various particles on the substrate, local heating, annealing, etc. Is deeper etched than. The parameters that change the reaction strength such as plasma long-lived radical formation conditions and photochemically excited reaction conditions are set so that almost no reaction occurs on the substrate when the electron beam is not applied, and when the electron beam is irradiated. It can be adjusted so that the reaction is promoted and etching occurs only there.
That is, the resistless pattern formation etching can be performed by finding such conditions. In some cases, the uneven surface of the etched wafer can be locally heated or annealed by an electron beam if the area is small. For this purpose, for example, according to known means, the relevant parameters such as the focusing condition and the scanning condition such as the spot size of the electron beam are appropriately selected, and the scanning is repeated in a state of being faster than the thermal response time of the substrate unit to make a unit area. The beam energy density per hit may be improved to a desired value, and the heating or melting portion may be moved little by little in the direction orthogonal to the scan width.

Further, regarding the light beam, at least one of the one or more light beams to be introduced is a light energy beam, so that the annealing by the electron beam and the annealing by the light energy beam are superposed at the same position on the substrate. You can also In this way, when the energy density is insufficient for annealing only by the electron beam, it can be compensated by the light beam according to a desired distribution ratio.

Regarding the oxidation process using reactively excited particles such as plasma oxidation, it is possible to control the depth of an oxide layer and pattern it, and to modify the film quality by pattern beam annealing during and after oxidation.

The electron beam drawing system shown in FIG. 1 is similar to a normal scanning type beam control system. However, this includes a known existing electron beam drawing system such as a variable shaped beam drawing system, An apparatus having an electron beam focusing control system similar to a known electron beam transfer system or the like may be used as long as the conditions are set appropriately. Of course, the electron beam referred to in this document is, as defined in this type of technical field, a known existing electron beam acceleration system or deceleration system, electron beam focusing / traveling system, and electron beam deflection system or electron beam optical system. Refers to a literal electron beam that can be scanned or controlled by.

Further, in such an electron beam optical focusing system for controlling and driving the electron beam, by appropriately controlling or changing various parameters, it is possible to appropriately adjust the electron beam energy and the spatial distribution of the beam bundle. The parameters can be selected, and the degree of freedom in design can be given to a certain extent with respect to the resistless pattern direct formation technique, which is the application of the present invention.

On the other hand, as the beam for photochemical excitation, various laser lights in the far ultraviolet region to the infrared region can be used. Also,
As the drawing mode, for example, the scanning or transfer of the electron beam is performed within one frame, and after the end of one frame, the step and repeat is repeated. On the other hand, conventionally, lithography with charged particles or a light beam,
As a pattern drawing technique using various beams, there is a technique of precisely moving a moving table on which a substrate is installed to form a desired pattern on the substrate in a manner of writing with a brush. It is applicable to the present invention.

According to the present invention, it is possible to form a sub-micron pattern on a substrate wafer by a resistless direct process in a vacuum exhaust system without exposing it to the atmosphere, and as a part of a direct pattern forming process expected to progress in the future. Can be used. This can contribute to improving the efficiency and performance of manufacturing various electronic devices, integrated circuits and the like.

[Brief description of drawings]

FIG. 1 is a view for explaining an embodiment of an electron beam fine pattern forming method in an atmosphere in which an atmosphere of plasma-excited reactive particles and an atmosphere of photochemically excited reactive particles of the present invention can be mixed. is there. In the figure, 1 is an electron gun, 2 is a diaphragm, 4 is an electromagnetic lens, 5 is a blanking plate, 6 is a diaphragm, 7 is an electromagnetic lens, 8a is a double polarization coil, 8b is a stigmator, 9 is an electromagnetic lens, 10 Is an aperture, 11 is an electron beam, 12 is a substrate, 13 is a substrate support, 1
4, 15 are X and Y moving mechanisms, 16 is a reaction chamber, 17, 18, 19, 20 are exhaust ports, 21 is a transport pipe, 22a is a microwave waveguide, 23 is a gas introduction pipe, and 24 is a light beam for photochemical reaction. , 25 are light flux control systems, 26, 2
Reference numerals 7 and 29 are reflecting mirrors, 28 is a transmission window, 31 and 32 are gas sources, and 30 is a gas introduction pipe.

Claims (5)

[Claims] 1. An electron beam focusing optical system is arranged in a reaction chamber so that differential evacuation is possible; the reaction chamber is housed in the reaction chamber in an atmosphere containing reactive excitation particles. The substrate is irradiated with an electron beam to which predetermined pattern information is given in advance from the electron beam focusing optical system; a predetermined substance is applied to the substrate due to a change in a substance due to a synergistic effect of the electron beam and the reactive excitation particles. The method of forming a fine pattern by using an electron beam. 2. The reactive excited particles are composed of long-lived radicals generated at a distance from the reaction chamber and transported to the reaction chamber. The method for forming a fine pattern as described in. 3. The reactive excitation particles are those excited by an electromagnetic light wave chemical reaction by a light beam introduced into the reaction chamber from outside the reaction chamber through a transmission window. The fine pattern forming method according to claim 1. 4. The reactive excitation particles are composed of long-lived radicals generated at a location remote from the reaction chamber and transported to the reaction chamber, and from the outside of the reaction chamber via a transmission window. The method for forming a fine pattern according to claim 1, wherein the method is excited by an electromagnetic light wave chemical reaction by a light beam introduced into the reaction chamber. 5. A plurality of light beams are introduced into the reaction chamber, and at least one of the light beams excites the reactive excitation particles by the electromagnetic light wave chemical reaction. 5. The fine pattern forming method as described in the above item 3 or 4.