JP2704949B2 - Manufacturing method of micro-electrostatic linear motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A micro-electrostatic linear motor has a process of forming an elongated groove in a semiconductor substrate with the object of providing a manufacturing method applying a semiconductor manufacturing technology. Forming a silicon nitride film covering the inner surface and filling the groove with silicon; and forming a silicon nitride film intermittently exposing the surface of the silicon body in the first cycle in the longitudinal direction on the silicon body filling the groove. Forming the silicon body into a periodic structure of a silicon region and a silicon oxide region by selective oxidation of the intermittently exposed portion of the silicon body; and forming the silicon body along the groove on both sides of the groove on the substrate. Forming an electrode that is intermittently buried in the second cycle and faces the side surface of the groove, and a step of removing the silicon nitride film surrounding the periodic structure by etching thereafter. Up The periodic structure by applying a voltage to said electrodes configured to the moving element to move in said groove.

[Industrial applications]

The present invention relates to a method for manufacturing a micro-electrostatic linear motor manufactured by applying a semiconductor manufacturing technique.

2. Description of the Related Art In recent years, attention has been focused on creating a minute machine of about several tens to several hundreds of micrometers on a semiconductor substrate by applying a semiconductor manufacturing technique.

These micromachines include gears, link mechanisms, electrostatic motors as drive systems, and the like. The mechanical operation amount is at most several tens of μm. Technology's cell operation mechanism, analytical equipment that handles small amounts of samples, micro mechanical sensors that detect mechanical quantities,
And so on.

The microelectrostatic linear motor according to the present invention is one of the electrostatic motors in the micromachine.

[Conventional technology]

FIG. 2 is a plan view illustrating a minute electrostatic linear motor.

This linear motor was proposed and proposed based on the contraction mechanism of muscles, and utilizes the phenomenon that a material with a high dielectric constant is more strongly drawn between counter electrodes to which a voltage is applied than a material with a low dielectric constant. .

That is, the mover 1 is formed in a rod shape by alternately joining the high dielectric constant bodies 2 and the low dielectric constant bodies 3 in the first cycle, and is movable in the longitudinal direction. Also, on both sides of the moving element 1, the moving element 1
The electrode 4 is intermittently fixedly arranged in the second cycle along the line.

Therefore, the amount of the high-permittivity substance 2 entering between the electrodes 4 opposed to each other with the movable element 1 interposed therebetween at an arbitrary position of the movable element 1 is gradually changing between the adjacent electrodes 4.

From this, it is possible to apply a voltage to the opposing appropriate electrode 4 to apply a thrust to the movable element 1 and to continuously move the movable element 1 by appropriately switching the electrode 4 to which the voltage is applied. Can be.

[Problems to be solved by the invention]

However, only the configuration of the above-mentioned micro-electrostatic linear motor has been proposed, but no specific manufacturing method using a semiconductor manufacturing technology has been proposed.

Therefore, an object of the present invention is to provide a manufacturing method using the semiconductor manufacturing technology with respect to the above-mentioned minute electrostatic linear motor.

[Means for solving the problem]

The object is to form an elongated groove in a semiconductor substrate, a step of forming a silicon nitride film covering an inner surface of the groove and filling the groove with silicon, and forming the silicon on a silicon body in which the groove is filled. Forming a silicon nitride film that intermittently exposes the surface of the body in a first cycle in the longitudinal direction, and selectively oxidizing the intermittently exposed portion of the silicon body to form the silicon body into a periodic structure of a silicon region and a silicon oxide region Forming an electrode intermittently buried in both sides of the groove of the substrate along the groove in a second cycle along the groove and facing the side surface of the groove; and Removing the silicon nitride film surrounding the periodic structure, wherein the periodic structure is a movable element that moves in the groove by applying a voltage to the electrode. .

(Operation)

The technologies required for the individual steps are all included in the semiconductor manufacturing technology.

The periodic structure released from the substrate in an embedded state with respect to the substrate by removing the silicon nitride film,
Since the dielectric constants of silicon and silicon oxide are about 12 and about 4, respectively, it can be a desired micro-electrostatic linear motor mover.

The arrangement of the electrodes provided on the substrate satisfies the configuration conditions of the minute electrostatic linear motor using the periodic structure as a moving element.

This makes it possible to manufacture a desired minute electrostatic linear motor by applying the semiconductor manufacturing technology.

〔Example〕

Hereinafter, an embodiment of a method for manufacturing a minute electrostatic linear motor according to the present invention will be described with reference to FIGS. 1 (a) to 9 (b). The numbers in parentheses in (1a) to (9b) represent different steps, a lower case a is a plan view, and b and c are BB cross-sectional views and CCs showing cut portions in (1a). It is a sectional view.

In FIG. 1, first, referring to (1a) and (1b), a groove 12 having an elongated shape and an inner surface substantially vertical or slightly inclined inward in a depth direction is formed in a silicon substrate 11 by well-known etching using a resist mask. To form The width of the groove 12 is about 2 μm,
The length is about 60 to 90 μm and the depth is about 1 μm.

Next, referring to (2b), a silicon nitride film 13 having a thickness of about 0.1 μm is formed on the surface of the substrate 11 including the inner surface of the groove 12 by CVD (chemical vapor deposition), and the groove 12 is filled by CVD. Deposit polysilicon until the surface is almost flat,
Etch back until the silicon nitride film 13 on both sides of the silicon body 15 is exposed, and fill the trench 12 with a silicon body 15 made of polysilicon.
To form

Next, referring to (3a), (3b) and (3c), silicon nitride is deposited to a thickness of about 0.1 μm by CVD, and is patterned by using a resist mask, so that the surface of the silicon body 15 is formed in the longitudinal first direction. A silicon nitride film 14 that is intermittently exposed at regular intervals is formed. The first period is 3 μm, the exposed length of the silicon body 15 is 1 μm, and the exposed width is the entire width of the silicon body 15. On both outer sides of the silicon body 14, the silicon nitride films 13 and 14 are integrated.

Next, referring to (4c), the exposed portion of the silicon body 15 is reduced to approximately half the thickness by etching with an HF + HNO ₃ solution using the silicon nitride film 14 as a mask.

Next, referring to (5c), the exposed portion of the silicon body 15 is selectively oxidized by thermal oxidation using the silicon nitride film 14 as a mask, and the silicon body 15 is formed into the periodic structure 18 of the silicon region 16 and the silicon oxide region 17. I do. The silicon oxide region 17 has a thickness substantially equal to the silicon region 16 due to an increase in volume of oxidation, and has a size substantially equal to the silicon region 16 due to expansion below the silicon nitride film 14. This periodic structure 18
Is a moving element of a linear motor to be manufactured.

Next, referring to (6a) and (6b), the silicon nitride film on both sides of the groove 12 is etched by using a resist mask.
After the removal of 13 and 14, the depression 19 is intermittently formed at both sides of the groove 12 in the second cycle by anisotropic dry etching using a new resist mask. Groove 12 and depression
The substrate 11 is made to remain at a thickness of about 0.3 μm between the side surfaces of 19, the second period is 2.5 μm, and the length of the depression 19 is
1.7 μm, width 1 μm, depth 1 μm.

Next, referring to (7b), an insulating film 20 made of silicon oxide having a thickness of about 0.2 μm is formed on the exposed surface of the substrate 11 including the inner surface of the depression 19 by thermal oxidation using the silicon nitride films 13 and 14 as a mask. . At this time, the silicon oxide region 17 exposed in the periodic structure 18 has a sufficient thickness already, so that the oxidation hardly progresses and increases. Note that the exposed portion of the silicon oxide region 17 may be covered with a silicon nitride film, and the silicon oxide insulating film 20 may be formed thicker. In this case, however, it is necessary to make the depression 19 larger than the above in consideration of the increase in the depression of the depression 19 due to the increase in the height of the insulating film 20.

Next, referring to (8a) and (8b), a titanium nitride film 21 having a thickness of about 200 ° is applied to the electrode 22 forming region on the insulating film 20 including the inner surface of the depression 19 by sputtering using a resist mask, An electrode 22 is formed by selectively depositing tungsten to a thickness of about 0.5 to 0.6 μm on the silicon nitride film 21 by CVD. The part extending from the depression 19 of the electrode 22 is a part to be a wiring. The sputtering can be performed by using a target of titanium and an atmosphere of nitrogen, and the selective CVD can be performed by using a reaction gas of SiH ₄ + WF ₆ or H ₂ + WF ₆ .

Next, referring to (9a) and (9b), the silicon nitride films 13 and 14 are removed by etching with an H ₃ PO ₄ solution to release the periodic structure 18 from the substrate 11, and the periodic structure 18 becomes a movable element. Complete the desired minute electrostatic linear motor.

This electrostatic linear motor has a period of 3 μm (first
Cycle) and the 2.5 μm cycle of electrode 22 arrangement (second cycle), the relative positional relationship between silicon region 16 and electrode 22 is calculated as
This is repeated at a period of μm.

Here, in order for the periodic structure 18 to function as a mover and move in the groove 12, a space is required on the extension of the groove 12, but this linear motor is arranged in parallel with the micromachine driven by the linear motor. Because the space is created by the periodic structure 18
May be formed in accordance with this micromachine during a step before the substrate is released from the substrate 11.

Note that the dimensions of each part described in the embodiment are merely examples, and the dimensions are not limited to the embodiment in view of the operation principle of the linear motor described above.

Further, the electrode 22 is not limited to the configuration of the embodiment. For example, a voltage buried in the substrate 11 may be a diffusion region of a conductivity type opposite to that of the substrate 11 by ion implantation, and a reverse bias voltage may be applied to the pn junction. May be applied. Furthermore,
The substrate 11 is not limited to silicon, but may be another semiconductor such as germanium or gallium arsenide.

〔The invention's effect〕

As described above, according to the configuration of the present invention, a manufacturing method using a semiconductor manufacturing technology is provided for a micro electrostatic linear motor. It has the effect of enabling promotion.

[Brief description of the drawings]

1 (a) to 9 (b) are a plan view and a cross-sectional view illustrating the steps of the embodiment, and FIG. 2 is a plan view illustrating a minute electrostatic linear motor. In the figure, 11 is a substrate, 12 is a groove, 13 and 14 are silicon nitride films, 15 is a silicon body, 16 is a silicon region, 17 is a silicon oxide region, 18 is a periodic structure (moving element), 19 is a depression, 20 Is an insulating film, 21 is a titanium nitride film, and 22 is an electrode.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Haruhisa Mori 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (1)

(57) [Claims] A step of forming an elongated groove in the semiconductor substrate; a step of forming a silicon nitride film covering an inner surface of the groove and filling the groove with silicon; Forming a silicon nitride film intermittently exposing the surface of the silicon body in a first cycle in the longitudinal direction; and selectively oxidizing the intermittently exposed portion of the silicon body to form the silicon body into a periodic structure of a silicon region and a silicon oxide region. Forming an electrode intermittently embedded in both sides of the groove of the substrate along the groove in a second cycle along the groove and facing the side surface of the groove; Removing the silicon nitride film surrounding the periodic structure, wherein the periodic structure is a movable element that moves in the groove by applying a voltage to the electrode. Linear motor The method of production.