EP3317730A1

EP3317730A1 - Spiral spring and method for producing same

Info

Publication number: EP3317730A1
Application number: EP16747909.6A
Authority: EP
Inventors: Stefan Männicke
Original assignee: Damasko Uhrenmanufaktur KG
Current assignee: Damasko Uhrenmanufaktur KG
Priority date: 2015-07-03
Filing date: 2016-07-01
Publication date: 2018-05-09
Also published as: WO2017006228A1; EP3989009A1; US20180142749A1

Abstract

The invention relates to a spiral spring (4) and to a method for producing the spiral spring (4). The spiral spring (4) has at least one winding (9), which consists of a solid core (16) composed of a silicon material (32). The core (16) comprises two long parallel and straight sides (22) and two short parallel and straight sides (24O, 24U). At least the opposite long sides (22) of the core (16) are covered by a SiO2 layer (20). In the method, the windings (9) are etched from the silicon material such that the core (16) of the at least one winding (9) of the spiral spring (4) is formed and comprises two long parallel and straight sides (22) and two short parallel and straight sides (24O, 24U).

Description

Spiral spring and method for its production

The present invention relates to a coil spring with at least one turn. The spiral spring consists of a solid core of a silicon material. The core comprises two long, parallel and rectilinear sides and two short parallel and rectilinear sides.

Furthermore, the invention relates to a method for producing a spiral spring for mechanical movements.

Likewise, the invention relates to a mechanical movement, which has incorporated the coil spring according to the invention.

State of the art

Oscillating systems for mechanical movements, especially for watches, are referred to in the art as a balance. The balance comprises a vibrating body, which is mounted pivotably about an axis of rotation by means of a balance shaft. Further, a spiral or balance spring is provided which forms the oscillatory and clocking system together with the mass of the oscillating body.

In the manufacture of coil springs tolerances can not be excluded. This applies to a greater extent to coil springs made of silicon, which are provided on their surfaces or outer surfaces to achieve the necessary strength and / or temperature independence with a uniform coating of silicon dioxide. As a rule, this coating takes place by thermal oxidation.

EP 1 422 436 A1 discloses a method for producing spiral springs for the oscillatory system of mechanical clocks made of monocrystalline silicon. The silicon core of the coil spring is completely encased in silicon dioxide.

European Patent Application EP 2 284 628 A2 discloses a resonator (coil spring) thermally compensated and having a monocrystalline core Owns silicon. The thermal oxidation of the coil spring is formed according to an embodiment such that at least one outer surface of the oscillating region of the core is provided with a coating and at least one other surface is provided with no coating. According to a further embodiment, the oscillating region of the core is provided with a coating on at least two adjoining outer surfaces, these coatings each differing in their thickness.

European Patent Application EP 2 589 568 A1 discloses a micromechanical part comprising a core of a semiconductor material and a coating of an electrically insulating material, such as e.g. Diamond or silicon dioxide. The coating is formed on a surface of the core. The core has an inner layer and an outer layer, wherein the electrical conductivity of the outer layer is greater than that of the inner layer.

Swiss patent application CH 699 780 A2 discloses a spring consisting of a silicon rod with an outer surface. The silicon rod has one

Young's modulus and a thermal expansion coefficient. A material is provided which partially compensates for the thermal coefficient, the material being Invar, Elinvar, Kovar or silica. The material is applied in the form of a cover on the silicon rod. International Patent Application WO 201 1/7072960 A1 discloses a thermally compensated resonator. The body of the resonator has a core of silicon material. The body or core carries at least a first and a second coating selected so that the thermal expansion is substantially zero. US Patent US 8,562,206 discloses a coil spring. In each turn of the coil spring a plurality of openings is provided which extend through the spiral of the spring. International Patent Application PCT / IB2015 / 054783 relates to a coil spring and a method of manufacturing a coil spring. The coil spring is provided with a coil spring attachment portion and an adjoining oscillation portion having at least one turn. The core of the spiral spring is made of silicon. At least two long side surfaces of the core connect at least two short side surfaces together. In at least one upper side surface and along one turn of the oscillation region, at least one depression is formed in a second partial region in the SiO ₂ layer, the depth of which extends at least as far as the silicon core. International patent application WO 2014/203086 A1 discloses a vibrating system for mechanical movements, a coil spring and a method for producing a spiral spring. The spiral spring is provided with a spiral spring attachment portion, an adjoining oscillation area with at least one turn and a stabilization area adjoining the oscillation area. A core of silicon has a substantially constant cross-section over the length of the vibration region prior to thermal oxidation. After the thermal oxidation, the spiral spring has at least a first partial region with a first height and at least one second partial region with a second height in the vibration region. The first height is greater than the second height.

Presentation of the invention

The object of the invention is to provide a coil spring which shows a permanently excellent vibration behavior, is distortion-free in the plane of the coil spring and has a stability against spring breaks. In addition, the coil spring is also reproducible in terms of vibration behavior, without neglecting the required temperature compensation.

This object is achieved by a coil spring according to claim 1. Another object of the invention is to provide a method for producing a spiral spring for mechanical movements, which is simple and reliable to perform and from which a spiral spring with a permanently excellent vibration behavior results, which also has the required temperature compensation and is distortion-free in the plane of the coil spring and has a stability against spring breaks.

This object is achieved by a method for producing a coil spring for mechanical movements according to claim 10.

A possible embodiment of the spiral spring is that the at least one turn of the spiral spring comprises at least one turn, which consists of a solid core of a silicon material. The core has two long parallel and rectilinear sides and two short parallel and rectilinear sides. To compensate for the coefficient of thermal expansion, at least the straight opposite long sides of the core are covered by a thermal expansion coefficient compensation layer. Preferably, the layer is a S1O2 layer.

A further embodiment of the spiral spring is that the upper short and rectilinear side and the two opposite long sides of a layer, preferably a S1O2 - layer, are enclosed. Another possible embodiment of the spiral spring is that it comprises at least one turn, which consists of a solid core of a silicon material. The core itself includes, among other things, essentially two long, parallel and rectilinear sides and two short, parallel and rectilinear sides. In this case, the upper, short and rectilinear side is connected on both sides via a respective continuously differentiable upper section with the opposite long sides. The opposite long and rectilinear sides, the respectively continuously differentiable upper portions connecting the upper short and rectilinear sides on both sides to the opposite long and rectilinear sides, and the upper short and rectilinear sides are covered by an S1O2 layer (20). The lower, short and rectilinear side is also connected to the opposite, long and rectilinear sides on each side by a continuously differentiable lower section. The core is covered by an S1O2 layer at least at the opposite, long and rectilinear sides and at least partially at the respective continuously differentiable upper portion and the respective continuously differentiable lower portion.

The spiral spring could be designed such that the two continuously differentiable upper sections differ from the continuously differentiable lower sections. According to one possible embodiment of the spiral spring, the short lower side and the short upper side are provided with an SiO 2 layer, so that the core is surrounded by an SiO 2 layer. The thickness and / or shape of the S1O2 layer differ on the lower short side and the upper short side. The thickness of the SiO 2 layer may be between 2pm and 5pm. The coil spring itself includes a coil spring attachment portion, a coil spring end portion, and at least one intermediate coil spring ring portion that includes the plurality of coils of the coil spring. The coil spring can be installed in a mechanical clock.

The core of the coil spring may consist of amorphous silicon, partially amorphous silicon, polysilicon, a monocrystalline silicon structure or a silicon sintered material. The spiral spring preferably consists of a polycrystalline silicon material. The polycrystalline silicon material can be produced in various ways. CVD deposition or epitaxial deposition of the polycrystalline silicon takes place, for example, in the form that the starting material thus obtained forms a thin layer or wafer whose thickness is then equal to or substantially equal to the thickness corresponding to the height of the spiral springs to be produced , Also, a CVD deposition for producing polycrystalline silicon is conceivable. In this case, first wafers or thin layers are obtained, from which then produced the coil springs become. Likewise obtained by the PVT process (Physical Vapor Transport (PVT)) by sublimation polycrystalline silicon. The polycrystalline silicon is formed by sublimation of silicon or silicon carbide on the barrier layer with the thickness which is then equal to or substantially equal to the thickness that is to have to be produced coil spring. Casting polycrystalline silicon is also possible. Another possibility for the production of polycrystalline silicon is the Siemens process. Wafers are cut from the silicon produced thereby and, if necessary, the required thickness is also lapped, which then substantially corresponds to the height of the spiral springs to be produced. The inventive method for producing a spiral spring made of a silicon material is configured according to a possible embodiment by the following steps:

Providing a carrier, wherein the carrier may be in the form of a wafer; Applying a silicon material to the carrier, wherein the silicon material forms a core of at least one turn of the spiral spring;

Etching the at least one turn of the coil spring so as to form the core of the at least one turn of the coil spring comprising two long, parallel and rectilinear sides and two short parallel and rectilinear sides; · Performing a thermal oxidation, wherein a layer of an oxide at least on the long sides defined and exposed side surfaces of the coil spring grows; and

Removing the carrier from the silicon material.

According to a possible embodiment of the method, in carrying out the thermal oxidation, the layer of oxide grows on the side surfaces defined and exposed by the long sides and on the side surface of the coil spring defined and exposed by the top, short and rectilinear sides. In one possible embodiment of the etching process of the at least one turn of the spiral spring, the core of the at least one turn of the spiral spring is formed. This results in two long, parallel and rectilinear sides and two short parallel and rectilinear sides. In this case, the upper, short and rectilinear side is connected on both sides via a respective continuously differentiable upper section with the opposite long sides.

In a further embodiment of the etching process of the at least one turn of the spiral spring, the core of the at least one turn of the spiral spring is formed. This results in two long, parallel and rectilinear sides and two short parallel and rectilinear sides. In this case, the upper, short and rectilinear side is connected on both sides via a respective continuously differentiable upper section with the opposite long sides. Similarly, a lower, short and rectilinear side is connected on both sides via a respective continuously differentiable lower section with the opposite long sides.

To form the continuously differentiable lower portion, the etching of the at least one turn of the spiral spring is designed such that an undercut is formed in the region of the lower side of the core. The undercut is formed such that at least the continuously differentiable lower portion, connecting the opposite long sides on either side to the lower short and rectilinear sides, is spaced from the carrier.

A further possibility of the configuration of the etching process is that a separating layer is provided between the carrier and the silicon material for the core of the at least one turn of the spiral spring. The etching of the at least one turn of the spiral spring is carried out such that in the region of the lower, short and rectilinear side of the core, an undercut is formed at least in the separating layer. By means of the back etching, at least the continuously differentiable lower portion, which connects the opposite long sides on both sides to the lower, short and rectilinear sides, is spaced from the carrier. Furthermore, the parameters of the etching process can be adjusted such that etched below an original level of the support. This means that material of the carrier is removed in certain areas.

Subsequent to the etching process, a layer of a material for compensating the coefficient of thermal expansion of the silicon material of the core of the windings is applied to the boundary surfaces of the at least one winding exposed by means of the etching process. Preferably, the material for compensating for the coefficient of thermal expansion is the same material as that of the separation layer. According to a particularly preferred embodiment, the material of the layer for compensating the thermal expansion coefficient of the silicon material is a Si0 ₂ layer. The Si0 ₂ layer is formed by thermal oxidation of the silicon material of the core. Finally, the removal of the carrier takes place, which can be carried out mechanically and / or chemically.

The "active vibration region" of the spiral spring extends from the inner end of the active vibration region adjoining the coil spring attachment portion of the spiral spring to the outer spring support point or spiral spring end section.

Another embodiment of the invention relates to a coil spring having a coil spring attachment portion, a coil spring end portion and at least one intermediate spiral spring ring portion having at least one turn. In general, the spiral spring ring portion has a plurality of turns. The coil spring has a solid and polygonal core of silicon material with at least two long sides and at least two short sides. Two opposite long sides together with an upper short side carry an S1O ₂ layer. The core has at the respective transitions of the upper, short side to the long sides an upper rounding or a continuously differentiable upper section. Further, the core has formed at the respective transitions of the lower short side to the long side a lower rounding and a continuously differentiable lower portion, respectively. The upper rounding and lower rounding are also covered by the S1O ₂ layer. The coil spring according to the invention has the advantage that it has the required mechanical stability for trouble-free vibration behavior, the necessary temperature compensation and freedom from distortion. In addition, the bearings of the coil spring are protected with the inventive and reduced in weight coil spring, which in turn has a positive effect on the accuracy of the clock and an extension of the service intervals.

In general, the core of the coil spring is rectangular and thus has two long sides and two short sides, which form two long side surfaces at least over the length of the vibration region by two long sides and two short side surfaces through the two short sides. The core thus has two opposite long side surfaces and two opposite short side surfaces.

In the case of the formed fillets (continuously differentiable sections of the core), e.g. also the radii of the upper rounding and the radii of the lower rounding. Just the fillets at the corners of the core avoid mechanical stress peaks, which in turn reduces the risk of breakage of the coil spring.

According to a possible embodiment, the spiral spring can also be provided on the lower short side with an SiO 2 layer. The S1O2 layer may have a smaller thickness on the lower side than the S102 layer on the upper short side or on the two long, parallel sides. In this embodiment, the S1O2 layer is deposited on the lower short side in a second stage of thermal oxidation. The duration of the thermal oxidation of the lower short side is selected such that an S 1O 2 layer with a smaller thickness grows than the thickness of the S 1O 2 layer on the two side surfaces and the upper side surface. The thickness of the S1O2 layer on the lower side surface formed by the lower short side is less than less than 2000 nm. The thickness is preferably in the range of 750 nm to 500 nm. The core of the spiral spring is preferably made of polysilicon. In the thermal oxidation of the core, upper fillets are formed at the respective transitions of the upper short side to the long sides, and lower fillets are formed at the respective transitions of the lower short side to the long sides. According to one embodiment of the method, a separating layer may be applied to the carrier on the carrier prior to the application of the material forming the core of the spiral spring on the carrier. Likewise, the material for the core of the coil spring may be provided with a release layer. The wafer with the material for the turns of the coil spring and the separating layer is z. B. gebonded to the carrier. The coil springs produced and exposed by the etching process are still connected to the material layer. The material layer with the coil springs can be at least partially removed from the carrier or from the carrier with the separating layer by mechanical and / or chemical processes. According to a possible embodiment, the carrier or carrier and the separating layer can be removed in a region which is smaller than the diameter of the carrier. This has the advantage that there is still sufficient material to handle at the edge for handling.

Likewise, it is possible that before the at least partial removal of the carrier, the separating layer, which is preferably likewise an SiO.sub.2 layer, is removed in the free regions by an etching process. After the subsequent removal of the support obtained cores of the spiral springs, which carry on the lower side of the separation layer of S1O2.

After the carrier or carrier and the release layer have been removed, further thermal oxidation can be performed on the upper short side and the opposite lower short side if it does not have a coating. The duration of the thermal oxidation is dimensioned such that the thickness (about 2000 nm) applied thereby of the oxide layer is smaller than the thickness of the oxide layer on the side surfaces and the upper side surface of the spiral spring. Preferably, the duration of the thermal oxidation is less than 1.5 hours, and more preferably the duration of the thermal oxidation is less than 1 hour.

Further advantageous aspects, details and embodiments of the invention will become apparent from the dependent claims, the description and the figures. In the following, embodiments of the invention and their advantages with reference to the accompanying figures will be explained in more detail. The proportions in the figures do not always correspond to the actual size ratios, as some shapes are simplified and other shapes are shown enlarged in relation to other elements for ease of illustration. 1 shows by way of example a perspective view of a vibration system for

Movements of mechanical watches according to the prior art;

FIG. 2 shows, by way of example, a section along a plane receiving the axis of the balance-wave shaft through the oscillating system of the movement according to FIG. 1; FIG. Fig. 3 by way of example a perspective side view of the exempted

Components of the vibration system according to Figures 1 and 2 for a clockwork;

Fig. 4 is a perspective view of the coil spring in conjunction with the

Balance wheel of a clockwork; Fig. 5 is a view of the cross section through a turn of the spiral, a

Core of a silicon material possesses;

Fig. 6A - 6D is a schematic representation of the flow of a possible

Embodiment of the method for producing a spiral spring;

7A-7D is a schematic representation of another embodiment of the

Procedure of the method for producing a spiral spring;

8A - 8C, a possible embodiment of the formation of the cross section of

Turns of a spiral spring; a schematic representation of the partial cross section of the coil spring in the upper region of the coil spring after the thermal oxidation; a schematic enlarged view of a cross section in which the individual turns of the coil spring have been exposed by etching of the surrounding silicon material; an enlarged view of a cross section in which the individual exposed turns of the coil spring, which were treated with a thermal oxidation, are still connected to the carrier; a schematic enlarged view of a cross section of the winding of the coil spring, which is surrounded due to the thermal oxidation with an oxide layer and the carrier is removed; a schematic enlarged view of a cross section of another embodiment in which the individual turns of the coil spring have been exposed by etching from the surrounding silicon material; an enlarged view of a cross section of the embodiment of Figure 13, in which the individual exposed turns of the coil spring, which were treated with a thermal oxidation, are still connected to the carrier. a schematic enlarged view of a cross section of the oxidized winding of the coil spring of Figure 14, in which the carrier is removed; a schematic enlarged view of a carrier with a separating layer, on which a layer of silicon material for the core of the turns of the coil spring is present; a schematic enlarged view of the layer of silicon material; from which the turns of the coil spring are etched; a schematic representation, wherein the etched windings are provided by thermal oxidation with an oxide layer; a schematic representation of the carrier with the windings, in which the oxide layer is completely removed and the separation layer at least partially; and Fig. 20 is a schematic representation of the turns, wherein the exposed portions of the side surfaces have again been subjected to thermal oxidation.

DETAILED DESCRIPTION OF THE DRAWINGS Identical reference numerals are used for the same or like elements of the invention. Furthermore, for the sake of clarity, only reference symbols are shown in the individual figures, which are required for the description of the respective figure.

For a better understanding of the present invention and the technical environment in which the invention is used, in connection with the figures 1 to 3 a known from the prior art oscillating system for mechanical movements will be described.

The oscillating system 1 comprises a vibrating body in the form of a flywheel 2, a balance shaft 3 and a coil spring 4. The flywheel 2 consists of an outer circular ring section 2.1, which is connected via a plurality of spokes 2.2 with a hub section 2.3. The hub portion 2.3 has a deviating from the circular, central through hole, in which an associated shaft portion 3 'of the balance shaft 3 is added, the concentric outer side makes a positive connection with the hub portion 2.3 of the flywheel 2. Thus, the flywheel 2 is rotatably connected to the balance shaft 3. In addition, at the center of rotation of the flywheel 2 facing inside of the outer annulus section 2.1 several inertia 2.4 are attached.

The balance-wheel shaft 3 also has an upper and lower free end 3.1, 3.2, which taper in a pointed manner and are received for the rotatable mounting of the balance-wheel shaft 3 about its axis UA in correspondingly formed upper and lower bearing units. In FIGS. 1 and 2, an upper bearing unit is shown by way of example. The axis UA of the balance shaft 3 is thus at the same time the axis of rotation of the flywheel 2 and the axis of the coil spring 4th The coil spring 4 consists of a preferably annular, inner coil spring attachment section 4.1 and an outer spiral spring end section 4.2. In between there are several spiral spring ring sections 4.3, which extend in a plane perpendicular and preferably concentric to the axis of the coil spring 4, which coincides with the axis UA of the balance shaft 3.

The preferably annular, inner coil spring mounting portion 4.1 is rotatably connected to the balance shaft 3, preferably glued and / or by positive engagement. For this purpose, the balance-wheel shaft 3 has a shaft section 3 "designed to receive the inner spiral-spring fastening section 4.1, which shaft section 3" is arranged above the shaft section 3 receiving the flywheel 2.

For in relation to the balance shaft 3 non-rotatable attachment of the outer Spiralfederendabschnitts 4.2, the holding assembly 5 is provided for adjusting the center of the coil spring 4. The holding arrangement 5 comprises at least one holding arm 6 and a holding element 7, which is fastened slidably in the region of the outer free end of the holding arm 6 along the longitudinal axis LHA of the holding arm 6.

The retaining arm 6 has an inner retaining arm end 6.1 and an outer retaining arm end 6.2, the inner retaining arm end 6.1 forming an open circular ring and an elongated guide recess 6.3 being provided in the region of the outer retaining arm end 6.2. The elongated guide recess 6.3 is provided for the variable attachment of the holding element 7 on the support arm 6. The inner retaining arm 6.1 is about unspecified holding means which can accommodate the upper and lower bearing units for rotatably supporting the balance shaft 3, rotatably attached, in such a way that the open circular ring of the inner retaining arm 6.1 surrounds the axis UA of the balance shaft 3 concentric ,

The holding element 7 has a substantially cylindrical, elongate base body 7.1 with an upper and lower end face 7.1 1, 7.12 and a longitudinal axis LHE, which has an open to the upper end 7.1 1 blind hole 7.2 with an internal thread for receiving a screw. 8 having. By means of the screw 8, which is guided by the elongated guide recess 6.3 of the support arm 6, the holding element 7 is firmly screwed to the support arm 6, in such a way that the longitudinal axis LHA of the support arm 6 and the longitudinal axis LHE of the support member 7 are perpendicular to each other. On the opposite lower end face 7.12 of the main body 7.1 of the holding element 7 is a perpendicular to the longitudinal axis LHE of the body 7.1 extending and downwardly open guide recess 7.3 is provided, which is formed for radially leading receiving the outer Spiralfederendabschnitts 4.2. A plane receiving the longitudinal axis LHE of the main body 7.1 divides the guide recess 7.3 approximately into two opposite, equal halves of the fork-shaped lower free end of the holding element 7.

In the assembled state is thus by means of the holding assembly 5 of the radial distance A between the axis UA of the balance shaft 3 and the longitudinal axis LHE of the holding element 7 and thus of the outer Spiralfederendabschnitts 4.2 adjustable. By a corresponding radial to the axis UA directed displacement of the holding element 7 and thus the outer Spiralfederendabschnitts 4.2, the coil spring center is adjustable, and preferably such that the Spiralfederringabschnitte 4.3 each have the same distance from one another and extend concentrically about the axis UA. Figure 4 shows a perspective view of a possible embodiment of the coil spring 4, which is rotatably connected with its coil spring mounting portion 4.1 with the balance shaft 3. The oscillation area LA form the spiral spring ring sections 4.3 of the spiral spring 4, which form the multiple turns of the spiral spring. The spiral spring ring portions 4.3 extend from an inner end 13 of the coil spring attachment portion 4.1 to a stabilization area LS and form the oscillation area LA. The embodiment of the stabilization region LS shown here represents one of several possible embodiments and should not be construed as limiting the invention. FIG. 5 shows a cross section 17 through a turn 9 of the spiral spring 4. The cross section 17 is substantially constant over the entire length of the turns 9 of the oscillation region LA. The turns 9 of a coil spring 4, which is produced for installation in the oscillating system 1 of a clock, consists of a core 16 of silicon material. The silicon material may, for example, consist of polycrystalline silicon, sintered silicon, or a monocrystalline silicon structure, etc. To compensate for the thermal expansion coefficient of the core 16 is at least partially surrounded by a layer of a material. In the embodiment illustrated here, the layer of material completely surrounds the core 16. It is obvious to a person skilled in the art that embodiments are also possible in which only side surfaces of the turns 9 of the spring are provided with the material for temperature compensation. In a preferred embodiment, the layer 20 is formed by thermally oxidizing the core 16. The formed layer 20 is an S1O ₂ coating with a thickness D between 2pm to 5pm. The cross section 17 has a height H and a width B. In this case, the cross section 17 is formed such that opposite long and straight sides 22 have a length L1 which is smaller than the height H. The lower short and rectilinear side 24u and the upper short and straight side 24 ₀ have a length L2 which is smaller than the width of the cross section 17. The core 16 is in the cross section 17 further designed such that the upper short and rectilinear side 24 ₀ on each side over a continuously differentiable upper portion 15 _0th is connected to the opposite long sides 22. Likewise, the lower short and rectilinear side 24u may be connected to the opposite long and rectilinear sides 22 of the core 16 on either side via a respective continuously differentiable lower portion 15u.

FIGS. 6A to 6D schematically show the sequence of a method for producing a micromechanical component, in particular a spiral spring 4 with its windings 9. A carrier 30 is provided on which the silicon material 32 can be applied in a layer thickness substantially the height of the core 16 of the coil spring 4 corresponds. Between the silicon material 32 and the carrier 30, a separating layer 31 is provided in this embodiment. The release layer 31 can be applied to the carrier 30. Subsequently, will then the silicon material 32 is applied to the release layer 31. Another possibility is that the separation layer 31 is applied to the silicon material 32. A wafer of the silicon material 32 with the separation layer 31 is bonded to the carrier 30, for example. Preferably, the release layer is S1O2. The deposition of silicon material 32 may be accomplished by a variety of prior art techniques known to those skilled in the art. Finally, a layer 33 is applied to the free surface of the silicon material 32 for the micromechanical component or spiral spring 4, which prevents the growth of an oxide during the thermal oxidation. In the embodiment of the method described here, this layer 33 z. B. a silicon nitride layer. The component or the windings 9 of the coil spring 4 are exposed by etching. Subsequently, a thermal oxidation is carried out, wherein an S1O2 - layer 20 is formed on the exposed surfaces of the component or the windings 9 of the coil spring 4. Finally, the detachment or separation of the layer of the silicon material 32, which contains the micromechanical components or the spiral springs 4, takes place from the carrier 30. The micromechanical components or the spiral springs 4 are still connected to the layer of the silicon material 32 for the micromechanical component The coil springs 4 are connected. The detachment or separation of the layer of the silicon material 32 from the carrier 30 can take place by means of chemical, mechanical or chemical-mechanical processes.

Figures 7A to 7D show a schematic representation of another embodiment of the procedure of the method for producing the turns 9 of a coil spring 4. Although the following description refers to the manufacture of a coil spring 4, this should not be construed as a limitation of the invention. Again, a release layer 31 is provided between the carrier 30 and the layer of silicon material 32. The release layer 31 between the support 30 and the layer of the silicon material 32 can be dispensed with. The layer of the silicon material 32 can thus be applied directly to the carrier 30. In the case of a separating layer 31, this is made of S1O2. Also, in this embodiment, no thermal oxidation inhibiting material is applied to the layer of silicon material 32 for the coil spring. After etching or exposing the windings 9 for the spiral spring 4, a first stage of the thermal oxidation takes place. The layer of the silicon material 32, which comprises the coil springs 4, is still connected to the carrier 30. In the first stage of the thermal oxidation, an S1O2 layer 20 is washed on the side surfaces defined by the long and rectilinear sides 22 (not shown here) and on the upper side surface of the core 16 of the spiral spring defined by the upper short and rectilinear side 24 ₀ , After the first stage of the thermal oxidation, the carrier 30 and here also the separating layer 31 are removed mechanically and / or chemically. A mechanical removal can be done eg by grinding.

After removing the carrier 30 thus defined by the lower, short and rectilinear side 24u lower side surface of the core 16 of the coil spring 4 is exposed. In a second stage of the thermal oxidation, in one embodiment of the method, an SiO 2 layer 20 can then also be applied to the lower side surface of the core 16 of the spiral spring 4. It is possible that the S1O2 layer 20 on the lower side surface of the core 16 has a smaller thickness than the S1O2 layer 20 on the remaining side surfaces of the core 16 of the coils 9 of the coil spring.

FIGS. 8A-8C show embodiments of the formation of the cross section 17 of the turns 9 of a spiral spring 4. The two opposite long sides 22 carry an S1O2 layer 20 at least over the length of the oscillation area LA. The core 16 has at least the upper short side 24 ₀ at the respective transitions to the long sides 22 formed the continuously differentiable upper portion 15 ₀ described in Fig. 5, which is also covered by the S1O2 - layer 20. In the embodiment shown in FIG. 8A, the S1O2 layer 20 on the upper short side 24 ₀ projects beyond the level of the core 16. On the surface of the turns 9 which is more definite by the upper short side 24 ₀ , there is no oxide layer present, that portion of the turns 9 was masked. This embodiment of the upper edge regions of the spiral spring 4 extends at least along the oscillation range of the spiral spring 4. FIG. 8B shows a further embodiment of the formation of the cross section 17 of the turns 9 of a spiral spring 4, wherein the core 16 carries a mask 34 (preferably silicon nitride) on the upper short side 24 ₀ . This embodiment of the upper edge regions of the spiral spring 4 extends at least along the vibration region. During thermal oxidation, an oxide in the form of a bird's beak grows between the thermal oxidation inhibiting mask 34 and the core 16 material. The masking 34 thus bulges. According to one possible embodiment, the mask may be at least partially removed along the oscillation range in the embodiment of the upper edge regions of the spiral spring 4.

Figure 8C shows a still further embodiment of the formation of the cross section 17 of the turns 9 of the coil spring. Here, the S1O2 layer 20 on the upper short side 24 _{0 is} removed down to the core 16. Likewise, one can remove the mask 34 described in Figure 8B so that the core 16 is exposed. The masking 34 and an upper part of the SiO 2 layer 20 are removed by the mechanical grinding process. It is also possible for the surface 35 of the windings 9 to be produced by etching with hydrofluoric acid (HF). This embodiment of the upper edge regions of the spiral spring extends at least along the oscillation region.

FIG. 9 illustrates an embodiment of the configuration of the cross section 17 of the turns 9 of the oscillation area of the spiral spring 4. The core 16 of silicon material carries a mask 34 on the side surface of the turns 9 defined by the short side 24 _0. The effect of the mask 34 is the thermal oxidation of the silicon material of the core 16 and the growth of the SiO 2 layer 20 in the region of the masking 34 proceeds differently and thus results in a different formation of the SiO 2 layer 20. The mask 34 is a diffusion barrier for oxygen. In a preferred embodiment, the mask 34 may consist of silicon nitride. At the side surfaces 22 of the core 16 is not covered by the mask 16 and thus freely accessible to oxygen. Due to the thermal oxidation, an S1O2 layer 20 grows on the side surfaces 22, the so-called "bird's beaks" 42 on both sides in the region of the continuously differentiable upper portion 15 forming ₀ , which extend below the mask 34. The mask 34 is consumed at the edges by the thermal oxidation.

Figure 10 is a schematic enlarged view of a cross section of the coils 9 of the coil spring exposed from the surrounding silicon material (not shown) by an etching process and still connected to the carrier 30. In the embodiment shown here, the carrier 30 is provided with a release layer 31. This separating layer preferably consists of S1O ₂ , the same material that grows on the core 16 of the windings 9 during the thermal oxidation.

The turns 9 of the coil spring 4 formed from the silicon material 32 (see FIG. 6A) by the etching process etched an etching height 50 and an etching width 51. By etching the soap surfaces or the long sides 22 of the turns 9 of the coil spring 4 are exposed. Likewise, the upper, short and rectilinear sides 24 ₀ and the lower, short and rectilinear sides 24u of the turns 9 are formed. The windings 9 are connected to the carrier 30 via the lower, short and rectilinear sides 24u via the remaining separating layer 31. The etching process of the windings 9 is designed in this embodiment such that between each two adjacent turns 9 is etched below an original level 52 of the carrier 30. Likewise, during the etching process, undercuts 53 are formed in the release layer 31. Also, the continuously differentiable upper portions 15o and the continuously differentiable lower portions 15u of the core 16 of the windings 9 are formed by the etching process.

Figure 11 shows the situation in which the windings 9 were subjected to thermal oxidation for a predetermined period of time after the etching process. Due to the thermal oxidation, an SiO ₂ layer 20 is formed on the freely accessible side surfaces of the core 16 of the windings 9. Likewise, there is a thermal oxidation of the carrier 30 and the deposition of a layer 55 at those points 54 of the carrier 30, which were exposed during the etching process. During the thermal oxidation, a portion of the silicon material of the core 16 in S1O ₂ is converted. The core 16 of each turn 9 is now completely of an S1O ₂ - Layer 20 surrounded. In the region of the lower, short and straight side 24u each winding 9 is connected via a S1O ₂ - bridge 25 connected with the carrier 30th

FIG. 12 shows the final processing step for producing a spiral 4 with a plurality of turns 9. The carrier 30 was completely removed (chemically and / or mechanically). The core 16 of the turns 9, which make up the spiral 4 (not shown here), is completely surrounded by an S1O ₂ layer 20 in this embodiment. In the windings 9 which have been produced according to this embodiment of the method, its upper cross-sectional shape 17 ₀ in the region of the upper, short and rectilinear side 24 ₀ differs from the lower cross-sectional shape 17 u in the region of the lower, short and rectilinear side 24 u. The difference in the upper cross-sectional shape 17 ₀ between the lower cross-sectional shape 17 u shown in the drawing is to be understood only as an example and should not be construed as a limitation of the invention. Depending on the setting parameters of the etching process and the parameters of the subsequent thermal oxidation, the extent of the difference between the upper cross-sectional shape 17 ₀ and the lower cross-sectional shape 17 u can be influenced.

Figure 13 is a schematic enlarged view of another embodiment of the cross-section of the coils 9 of the coil spring exposed by the surrounding silicon material (not shown) by an etching process and still connected to the carrier 30. In the embodiment shown here, the carrier 30 is provided with a release layer 31. This separating layer preferably consists of S1O ₂ , the same material that grows on the core 16 of the windings 9 during the thermal oxidation. The turns 9 of the spiral spring 4 formed by the etching process etched an etching height 50 and an etching width 51. By etching the soap surfaces or the long sides 22 of the turns 9 of the coil spring 4 are exposed. Likewise, the upper, short and rectilinear sides 24 ₀ and the lower, short and rectilinear sides 24u of the turns 9 are formed. The windings 9 are connected to the carrier 30 via the lower, short and rectilinear sides 24u via the separating layer 31. The separation layer 31 may be made of the same material as the layer 20 for the compensation of the thermal Expansion coefficient is applied to at least one side surface of the turns 9 of the coil spring.

Figure 14 shows the situation in which the windings 9 after the etching process were subjected to thermal oxidation for a predetermined period of time. As a result of the thermal oxidation, an S1O ₂ layer 20 is formed on the freely accessible side surfaces of the core 16 of the windings 9, for example. During the thermal oxidation, a portion of the silicon material of the core 16 in S1O ₂ is converted. The core 16 of each winding 9 is now surrounded by an S1O ₂ layer 20 on the freely accessible side surfaces. In the area of the lower, short and rectilinear side 24 u, each turn 9 is still connected to the carrier 30.

FIG. 15 shows the final processing step for producing a spiral 4 with a plurality of turns 9. The carrier 30 and also the separating layer were completely removed in this embodiment (chemically and / or mechanically). The core 16 of the turns 9, which make up the spiral 4 (not shown here), in this embodiment is surrounded by an S1O ₂ layer 20 at the side surfaces defined by the long sides 22 and by the upper, short and rectilinear sides 24 ₀ , At the side surface defined by the lower, short and rectilinear side 24u, there is no S1O ₂ layer 20 since the separating layer has also been removed. Likewise, in an additional thermal oxidation process, an oxide layer 20 can also be applied to the lower, short and rectilinear side 24u.

In FIG. 16 to FIG. 20, a further embodiment of a method is described with which the width of the oxidized windings 9 of the spiral spring 4 can be set precisely. FIG. 16 describes the structure of a carrier 100, which in this embodiment is provided with a separating layer 101. On the separating layer 101, a material layer 102 for the core 16 of the turns 9 of the coil spring 4 is applied. As already mentioned, this is only one of several possible embodiments of the invention and should therefore not be construed as limiting. In the illustration of FIG. 17, the turns 9 of the spiral spring 4 having an etching width 105 and an etching height 107 are etched in the material layer 102. By etching the soap surfaces 1 10 and side walls of the turns 9 of the coil spring 4 are exposed. The separation layer 101 can serve as a stop layer for the etching process of the windings 9. Likewise, in the etching process, the upper side surface 1 1 1 is formed. Figure 18 shows the situation in which the windings 9 have been subjected to thermal oxidation for a predetermined period of time after the etching process. As a result of the thermal oxidation, an SiO 2 layer 20 is formed on the two freely accessible side surfaces 11 and the freely accessible upper side surface 11 1 1. During the thermal oxidation, part of the silicon material of the core 9 is converted to S1O2. The original etching width 105 of each winding 9 of the core is thereby reduced to a smaller oxidation width 106 of the core 16 of the winding 9. Likewise, the original etching height 107 of a winding 9 is reduced to the oxidation level 108 by the thermal oxidation. By the etching process, the core 9 can form 9R roundings. Consequently, the one S1O2 layer 20 also forms fillets 20R.

In FIG. 19, the next step of a further method according to the invention for producing a spiral spring 4 is shown graphically. In the subsequent step after the thermal oxidation, the S1O2 layer 20 of Figure 18 is removed. The removal of the SiO.sub.2 layer 20 takes place by methods which are well known to a person skilled in the art. When the S1O2 layer 20 is removed, at least part of the separating layer 101 is also removed. As a result, windings 9 are obtained for the spiral spring which have the oxidation width 106 and the oxidation height 108 as dimensions. Furthermore, due to the at least partial removal of the separating layer 101, at least a portion of the lower side surface 1 12 can be exposed and thus accessible. The removal of the separating layer 101 is adjusted such that the lower side surface 12 of the turn is connected to the carrier 100 via a web 15 of the separating layer 101.

In Figure 20, the final processing step of the turns 9 is shown. The carrier 100, on which a plurality of spirals are formed with their windings 9, is subjected to a renewed thermal oxidation. Because the Side surfaces 1 10, the upper side surface 1 1 1 and at least a portion of the lower side surface 1 12 are freely accessible, is formed on this by the thermal oxidation of a S1O2 - layer 20. As already mentioned in the description of FIG. 18, part of the silicon material of the core of the turns 9 is also converted into S1O2 during this thermal oxidation. This results in a core of the winding 9 of silicon material (eg polysilicon), which has a width 120 and a height 130 which is smaller than the oxidation width 106 and the oxidation height 108. The webs 1 15 keep the coil springs still on the carrier 100th To release the coil springs, the carrier 100 is removed by conventional methods. The bars 1 15 can stop or be completely removed. The reoxidation has the advantage that the width 120 and the height 130 of the turns 9 of the coil spring can be set exactly. Thus, it is possible to adjust the mechanical properties of the coil spring in a desired manner.

The manufacturing methods described herein have the advantage that spiral springs of silicon material (e.g., polysilicon) can be fabricated without distortion. Furthermore, the coil springs thus produced have a permanently excellent vibration behavior and have a stability and resilience against spring breaks. In addition, the spiral spring is also reproducible in terms of vibration behavior, without neglecting the required temperature compensation. LIST OF REFERENCE NUMBERS

1 vibration system

2 flywheel

2.1 circular ring section

2.2 spoke 2.3 hub section

2.4 flywheel balance staff

shaft section

upper free end

lower free end

spiral spring

Coil spring mounting section

Spiralfederendabschnitt

Spiral spring ring section

holding assembly

holding arm

inner retaining arm

outer retaining arm

guide recess

retaining element

body

Blind hole 7.3 guide recess

7.1 1 upper end side

7.12 lower end

8 screw

9 turn

9R rounding

13 inner end

15 ₀ continuously differentiable upper section

15u continuously differentiable lower section 16 core

17 cross section

170 cross-sectional shape

17U cross-sectional shape

20 layer, SiO ₂ layer

20R rounding

22 long side

24 ₀ top, short and straight side

24u lower, short and straight side 25 bridge, Si0 ₂ bridge

30 carriers

31 separating layer

32 silicon material 33 layer

34 masking

35 surface

42 bird's beak

50 etching height

51 etching width

52 original level

53 undercut

54 vacancies

55 shift

100 carriers

101 separating layer

102 material layer 105 etching width 106 oxidation width

107 etching height

108 oxidation level

1 10 soap surfaces

1 1 1 upper side surface 1 15 bridge

120 width

130 height

A distance

B width

H height

L1 length

L2 length

LA vibration range

LS stabilization area

LHA longitudinal axis

LHE longitudinal axis

UA axis

Claims

claims

1 . Helical spring (4) having at least one turn (9) consisting of a solid core (16) of a silicon material (32), the core (16) having two long, parallel and rectilinear sides (22) and two short parallel and rectilinear

Sides (24 ₀ , 24u), characterized in that at least the opposite long sides (22) of the core (16) are covered by an S1O2 layer (20).

A coil spring (4) according to claim 1, wherein the upper short and rectilinear sides (24 ₀ ) and the opposite long sides (22) of an S1O 2 layer

(20) are enclosed.

3. coil spring (4) according to claim 1, wherein the upper short and rectilinear side (24 ₀ ) on both sides via a continuously differentiable upper portion (15 ₀ ) with the opposite long sides (22) is connected; and the opposed long and rectilinear sides (22), each having continuously differentiable upper portions (15 ₀ ) connecting the upper short and rectilinear sides (24 ₀ ) on either side with the opposite long and rectilinear sides (22), and the upper short one and rectilinear side (24 ₀ ) are covered by a Si0 ₂ layer (20).

A coil spring (4) according to claim 3, wherein the lower short and rectilinear sides (24u) are covered by an S1O2 layer (20) which is thicker in thickness than the S1O2 layer (20) on the opposite long sides (24). 22) and the S1O2 layer (20) on the top, short and rectilinear sides (24 ₀ ).

5. spiral spring (4) according to claim 1, wherein the upper short and rectilinear side (24 ₀ ) on both sides via in each case a continuously differentiable upper portion

(150) is connected to the opposite long sides (22); the lower short and rectilinear side (24u) is connected on both sides via a respective continuously differentiable lower portion (15u) to the opposite long and rectilinear sides (22) and the core (16) at least to the opposite long and rectilinear sides (22) and at the respective continuously differentiable upper section (15 _Q ) and the respective, continuous differentiable lower portion (15u) of a S 1O2 - layer (20) is covered.

6. coil spring (4) according to claim 5, wherein the two continuously differentiable upper portions (15 _Q ) of the lower, continuously differentiable sections

(15u) differ.

The helical spring (4) of claim 5, wherein the lower short side (24u) and the short upper side (24 ₀ ) are provided with an S1O2 layer (20) such that the core (16) is of a S1O2 layer (20) is surrounded, with the thickness and / or shape of the S1O2 - layer (20) on the lower short side (24u) and the upper short side (24 _Q) are different.

8. coil spring (4) according to the preceding claims, wherein the coil spring (4) comprises a coil spring attachment portion (4.1), a Spirfederfederendabschnitt (4.2) and at least one intermediate spiral spring ring portion (4.3).

9. Mechanical clock with a coil spring (4) according to claims 1 to 8.

10. A method for producing a spiral spring (4) made of a silicon material, characterized by the following steps:

• providing a carrier (30);

Depositing a silicon material (32) on the support (30), the silicon material (32) forming a core (16) of at least one turn (9) of the coil spring (4);

Etching the at least one turn (9) of the spiral spring (4) so that the core (16) of the at least one turn (9) of the spiral spring (4) is formed, comprising two long, parallel and rectilinear sides (22) and two includes short parallel and rectilinear sides (24 ₀ , 24u);

Performing a thermal oxidation wherein a layer (20) of oxide grows at least on the side faces of the coil spring defined and exposed by the long sides (22); and

Removing the carrier (30) from the silicon material (32).

1 1. The method of claim 10 wherein, in performing the thermal oxidation, the layer (20) of oxide faces the exposed side surfaces defined by the long sides (22) and the side surface defined by the top, short and rectilinear sides (24 ₀ ) Spiral spring grows up.

12. The method of claim 10, wherein the upper, short and rectilinear side (24 ₀ ) on both sides via a respective continuously differentiable upper portion (15 ₀ ) with the opposite long sides (22) is connected and wherein when performing the thermal oxidation, the layer (20) of the oxide grows on the side surfaces defined and exposed by the long sides (22), the continuously differentiable top portions (15 ₀ ) and the top, short and rectilinear sides (24 ₀ ).

13. The method of claim 10, wherein the upper, short and rectilinear side (24 ₀ ) on both sides via a respective continuously differentiable upper portion (15 ₀ ) with the opposite long sides (22) is connected and a lower, short and rectilinear side ( 24u) is connected on both sides via a respective continuously differentiable lower portion (15u) with the opposite long sides (22)

14. The method of claim 13, wherein the etching of the at least one turn (9) of the coil spring (4) is carried out such that in the region of the lower side (24u) of the core (16) an undercut (53) is formed, so that at least the continuously differentiable lower portion (15u) connecting the opposite long sides (22) on both sides to the lower, short and rectilinear sides (24u) is spaced from the support (30).

15. The method of claim 13, wherein between the carrier (30) and the silicon material (32) for the core (16) of the at least one turn (9) of the coil spring, a separating layer (31) is provided and the etching of at least one turn ( 9) of the spiral spring (16) is designed such that in the region of the lower, short and rectilinear side (24u) of the core (16) an undercut (53) is formed at least in the separating layer (31), so that at least the continuously differentiable lower portion (15u) connecting the opposite long sides (22) on either side with the lower, short and rectilinear sides (24u) is spaced from the support (30).

The method of claim 15, wherein the etching of the at least one turn (9) of the coil spring (16) is performed to etch below an initial level (52) of the carrier (30).

17. The method according to claim 10, wherein a layer (20) of a material for compensating the thermal expansion coefficient of the silicon material of the core (16) of the windings (9) is exposed to the boundary surfaces of the at least one winding (9) exposed by the etching process ) is applied.

18. The method according to claim 17, wherein the thermal expansion coefficient compensating material is the same material as that of the separating layer (31).

19. The method of claim 17, wherein the material of the thermal expansion coefficient compensation layer of the silicon material is a SiO 2 layer formed by thermal oxidation of the silicon material of the core.

20. The method according to any one of claims 10 to 19, wherein the removal of the carrier (30) is carried out mechanically and / or chemically.

21. A mechanical watch with a coil spring (4) made according to the method of any one of claims 10 to 20.