JPH06146027A - Production of micromachine - Google Patents

Abstract

PURPOSE:To provide the micromachine capable of executing fine working of a high degree by using an etching gas for forming chemical species of a halogen system and free sulfur and etching a base body consisting of a silicon material while depositing the sulfur. CONSTITUTION:Resist patterns 2 are formed on a base body 1 to be etched and this base body is set on the stage of a microwave plasma etching device. The base body is kept at about <=-70 deg.C and is etched by using gaseous S2F2. The F radicals dissociated and formed from the gaseous S2F2 act as etching species and the etching of the base body 1 progresses. The S released into the plasma at this time deposits on the side wall surfaces of the base body 1 which is kept cooled, by which protective films 3 for the side walls are formed and, therefore, the etching of the base body 1 progresses only in its depth direction. The protective films 3 and the patterns 2 are then removed and thereafter an oxidized film (SiO2)4 is formed over the entire surface of the base body 1. A laminate 5 consisting of polycrystalline silicon is deposited on this oxidized film 4 by using a gaseous mixture composed of SiH4/He/N2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a micromachine for constructing a so-called micromachine called a very micromachine system.

[0002]

2. Description of the Related Art Recently, attempts have been made to construct a minute mechanical system (micromachine) having a motion mechanism called an actuator in addition to a sensor and an electronic circuit on a substrate made of a silicon material. In manufacturing such a micromachine, an advanced fine processing technology based on a photolithography process used for manufacturing a VLSI or the like is adopted.

That is, in manufacturing a conventional micromachine, shape processing by anisotropic etching is incorporated in the process, and as an etching gas for performing this, Freon 113 (C ₂ Cl ₃ F _{3) is used.} ), So-called CFCs (chlorofluorocarbons)
System gases are widely used.

In the fine processing using the CFC-based gas, the carbon-based polymer generated in the plasma exerts a side wall protection effect, so that a desired processed shape is formed under the resist patterned into a predetermined shape. can get.

[0005]

However, in the above-mentioned conventional manufacturing method, the carbon-based polymer deposited from the gas phase on the side wall of the substrate to be etched is not completely removed during the removal process, and becomes an etching residue. There has been a problem that the subsequent workability is significantly reduced. In the past, CFCs have been used for anisotropic etching, which is a means of manufacturing micromachines. However, from the perspective of preventing the ozone layer from depleting the earth, their manufacture and use will be totally prohibited in the near future. Therefore, there is an urgent need to establish a microfabrication technique that can replace the conventional method.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for manufacturing a micromachine capable of performing high-level fine processing without using a fluorocarbon gas.

[0007]

The present invention has been made to achieve the above object, and uses an etching gas capable of producing free sulfur and halogen-based chemical species in plasma under discharge dissociation conditions. The method for manufacturing a micromachine includes a step of holding a substrate to be etched made of a silicon material at room temperature or below and performing etching while depositing free sulfur on the substrate.

After the etching is completed, the substrate to be etched is heated to remove the sulfur deposited on the substrate to be etched by sublimation.

[0009]

In the method for manufacturing a micromachine of the present invention, the free halogen-based chemical species act as the main enching species, and the etching of the substrate to be etched made of the silicon-based material proceeds. On the other hand, the free sulfur generated in the plasma is deposited on the substrate to be etched kept at room temperature or below to form a side wall protective film, which has a side wall protective effect. As a result, a good processed shape without undercut is obtained under the resist patterned into a predetermined shape. After the etching is finished, the substrate to be etched is heated to remove the sulfur deposited on the substrate to be etched by sublimation, whereby a clean processed surface having no etching residue can be obtained on the substrate to be etched.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 and 2 are views for explaining an embodiment of a method for manufacturing a micromachine according to the present invention. Here, the most feature of the present invention is that, as a method for manufacturing a micromachine, an etching gas that can generate free sulfur and halogen-based chemical species in plasma under discharge dissociation conditions is used, and the method is made of a silicon-based material. It has a step of etching while keeping the substrate to be etched below room temperature and depositing free sulfur on the substrate, and after etching is finished, the substrate to be etched is heated and deposited on the substrate to be etched. The point is to remove the sulfur by sublimation, and a specific example thereof will be described below.

In this embodiment, a method for manufacturing a micromachine using a substrate to be etched made of single crystal silicon as a silicon material and S ₂ F ₂ gas as an etching gas will be described. First, as shown in FIG. 1A, a resist pattern 2 having a predetermined shape (for example, a circle) is formed on a substrate 1 to be etched by resist patterning. Subsequently, the substrate 1 to be etched is set on the mounting table of the microwave plasma etching apparatus, and an ethanol refrigerant is sequentially supplied to the mounting table from the chiller connected to the outside to set the etching target on the mounting table. The substrate 1 is cooled and held at room temperature or lower, for example, at −70 ° C., and from this state, etching is performed under the following conditions as an example. S ₂ F ₂ flow rate 5 sccm Gas pressure 10 mTorr Microwave power 850 W RF bias 30 W (2 MHz) Substrate temperature −70 ° C.

Here, the above S ₂ F ₂ is one of various sulfur halides, and in this embodiment, F radicals dissociated and produced from the S ₂ F ₂ gas by microwave discharge act as the main etching species, Etching of the etching substrate 1 proceeds. At that time, S released into the plasma
(Sulfur) is deposited on the side wall surface of the substrate 1 to be etched, which is cooled and held at room temperature or lower (-70 ° C. in this example), and the side wall protective film 3 is formed in that portion, and exhibits the side wall protective effect. As a result, the etching of the substrate 1 to be etched proceeds only in the depth direction thereof, so that a good processed shape without undercut or the like can be obtained under the resist pattern 2.

Subsequently, when the above etching is completed, the substrate 1 to be etched is heated to a predetermined temperature this time. In this embodiment, the etching target substrate 1 is heated to 90 ° C. or higher to remove the side wall protective film (sulfur) 3 deposited on the side wall surface of the etching target substrate 1 by sublimation. As a result, a clean processed surface having no etching residue can be obtained on the substrate to be etched 1. The resist pattern 2 formed on the substrate 1 to be etched is removed by ashing.

Next, as an example, the entire surface of the substrate 1 to be etched is oxidized under the following conditions to form an oxide film (SiO ₂ ) 4 on the substrate 1 to be etched as shown in FIG. 1 (b). Dry O ₂ flow rate 6 l / min Processing temperature 850 ° C. Film thickness 100 nm

Then, using a mixed gas of SiH ₄ / He / N ₂ , as an example, a stacked body 5 made of polycrystalline silicon is deposited on the oxide film 4 under the following conditions (see FIG. 1C). SiH ₄ flow rate 100 sccm He flow rate 400 sccm N ₂ flow rate 200 sccm Gas pressure 70 Pa Processing temperature 610 ° C. Film thickness 0.3 μm

Subsequently, resist patterning is performed to form a resist pattern 6 on the laminate 5, and the laminate 5 is anisotropically etched under the following conditions as an example. S ₂ F ₂ flow rate 5 sccm Gas pressure 10 mTorr Microwave power 850 W RF bias 30 W (2 MHz) Substrate temperature −70 ° C.

After the anisotropic etching is completed, the side wall protective film (not shown) on the laminated body 5 is removed by sublimation and the resist pattern 6 previously formed is removed by ashing as described above. A processed shape as shown in FIG. 2B is obtained.

Finally, for example, the work piece is dipped in a solution of diluted hydrofluoric acid to remove only the oxide film 4 by selective etching. As a result, the so-called spindle 1 as shown in FIG.
A micromachine including a and a rotating body (laminated body 5) is manufactured.

In the above embodiment, the rotating body is formed by the laminated body 5 made of polycrystalline silicon. However, for example, WF ₂ / SiH _{4 is changed} from the state shown in FIG.
If WSi ₂ (tungsten silicide) is deposited on the oxide film 4 using a mixed gas of He / He, and resist patterning is performed on this to perform anisotropic etching, it is possible to manufacture a micromachine with superior durability. Becomes

Although S ₂ F ₂ is used as the etching gas in the above-mentioned embodiments, the etching gas used in the present invention is free sulfur and halogen-based chemical species in plasma under discharge dissociation conditions. Any material that can be used is used.
₂ , SF ₄ , SF ₁₀ , chlorine-based S ₂ Cl ₂ , S
₃ Cl ₂ , SCl ₂ , bromine-based S ₂ Br ₂ , S ₃
Br ₂ , SBr _{2 and the} like can be mentioned. Furthermore, in the present embodiment, the method of manufacturing a micromachine including a spindle and a rotating body has been described, but the present invention is not limited to this, and is widely applied to manufacture of a micromachine including various sensors and micro vacuum tubes. can do.

[0021]

As described above, according to the method for manufacturing a micromachine of the present invention, it is possible to perform high-level fine processing without using a fluorocarbon gas as in the conventional case.
This will greatly contribute to the protection of the earth's environment, and the establishment of a microfabrication technique that will replace the CFC-based gas ban, which is expected to be implemented in the near future, will be realized.
Further, in the manufacturing method of the present invention, since the sidewall protective film deposited on the substrate to be etched is removed by sublimation, no etching residue is generated on the substrate to be etched.
The deterioration of workability due to etching residues, which has been a concern in the past, is solved.

[Brief description of drawings]

FIG. 1 is a diagram (No. 1) for explaining an embodiment of a method for manufacturing a micromachine according to the present invention.

FIG. 2 is a diagram (No. 2) for explaining one embodiment of the method for manufacturing a micromachine according to the present invention.

[Explanation of symbols]

 1 Etched Substrate 2 Resist Pattern 3 Sidewall Protection Film (Sulfur) 4 Oxide Film 5 Laminate

Claims (2)

[Claims] 1. An etching gas capable of generating free sulfur and halogen-based chemical species in plasma under discharge dissociation conditions is used, the substrate to be etched made of a silicon-based material is kept at room temperature or below, A method of manufacturing a micromachine, comprising the step of etching while depositing sulfur on the etching substrate. 2. After the etching is completed, the substrate to be etched is heated to remove the sulfur deposited on the substrate to be etched by sublimation.
A method for manufacturing the described micromachine.