Patent Publication Number: US-11042124-B2

Title: Timepiece component and method of manufacturing timepiece component

Description:
TECHNICAL FIELD 
     The present invention relates to a timepiece component constituting a machine component in a timepiece and a method of manufacturing a timepiece component. 
     BACKGROUND ART 
     In a mechanical timepiece, a speed governor (balance) is conventionally used that is made up of a hairspring and a balance wheel (with a balance staff) and that operates a drive mechanism (movement) while keeping a constant speed with regularity. The balance wheel regularly performs a reciprocating rotary motion according to extension and contraction of a so-called isochronous hairspring keeping a constant speed with regularity. To the balance, an escapement made up of an escape wheel and an anchor is coupled, and energy from the hairspring is transferred to sustain operation (vibration). 
     In general, a hairspring formed by processing metal is widely known. A hairspring formed by processing metal may not be shaped as designed in some cases due to variations in processing accuracy, effects of internal stress of metal, etc. If the hairspring required to regularly vibrate the balance cannot be formed in a shape as designed, the balance wheel cannot perform the isochronous motion. In this case, deviation in the so-called rate of the timepiece occurs expressed as a certain amount of advance or delay of the timepiece per day. 
     In recent years, attempts have been made to manufacture a timepiece component by etching processing of a silicon substrate. The timepiece component formed by etching processing of a silicon substrate may be reduced in weight as compared to timepiece components formed by using conventional metal components. Additionally, the timepiece component formed by etching processing of a silicon substrate may be mass-produced with precision. Therefore, small lightweight timepieces are expected to be manufactured by using timepiece components formed by etching processing of a silicon substrate. 
     A reactive ion etching (RIE) technique is a dry etching technique and may be used for etching a silicon substrate. RIE techniques have advanced in recent years and, among the RIE techniques, a Deep RIE technique has been developed to enable etching with a high aspect ratio. By etching a silicon substrate by using the RIE technique, a mask pattern may be faithfully reproduced in a vertical depth direction without etching going under a portion masked by photoresist, etc., and a timepiece component having a shape as designed may be manufactured accurately. 
     A timepiece component formed by using silicon has better temperature characteristics than metal and is more resistant to deformation resulting from environmental temperature as compared to a conventional hairspring formed by using metal. Therefore, it is conceivable that a dry etching technique such as the RIE technique may be applied to a timepiece component constituting a speed governing mechanism of a timepiece. On the other hand, since silicon is a brittle material, a timepiece component formed by using silicon may be damaged when subject to a strong impact. 
     To eliminate such trouble, in a conventional technique, for example, an opening portion is provided in an upper surface of a spring unit forming one flat surface in a planar view of a hairspring so as to reduce the mass of the hairspring, so that the hairspring is minimally affected by impacts while rigidity equivalent to a hairspring without the opening portion is maintained (see, for example, Patent Document 1).
     Patent Document 1: Japanese Laid-Open Patent Publication No. 2012-21984   

     DISCLOSURE OF INVENTION 
     Problem to be Solved by the Invention 
     However, the conventional technique described in Patent Document 1 described above has a problem in that since the provision of the opening portion reduces a thickness of a portion of the opening portion, the strength around the opening portion becomes insufficient and may result in damage of the hairspring when the timepiece is subject to a strong impact. In particular, for example, the size of the hairspring varies depending on the size, etc. of the timepiece incorporating the hairspring and, in the case of a typical wristwatch, a hairspring with a diameter of about 5 mm to 8 mm is used. 
     In a hairspring having such a diameter, the width of the upper surface of the portion constituting the spring unit is several dozen μm, and the conventional technique described in the patent document 1 described above has a problem in that since the opening portion is provided in such a thin portion, the spring unit is more susceptible to damage. Such a hairspring is damaged, for example, when the timepiece is subject to a strong force, resulting in contact between adjacent coil-shaped spring units. 
     Additionally, when some kind of impact is applied to a hairspring formed by using a brittle material such as silicon, stress concentrates at a corner of the hairspring. Therefore, when the timepiece is subject to a strong impact, the corner of the hairspring chips or cracks due to the force. If the hairspring is damaged or a portion thereof is chipped, the balance wheel cannot perform a regular reciprocating rotary motion and becomes unable to function as a timepiece. Moreover, a broken piece of the damaged hairspring entering a drive mechanism causes a problem in that a fatal failure may occur in the timepiece itself. 
     To solve the problems of the conventional technique described above, it is an object of the present invention to provide a timepiece component and a method of manufacturing a timepiece component that is highly accurate in terms of manufacturing, that enables a weight reduction, and that is resistant to breaking and capable of exhibiting high strength even when a strong external impact is applied. 
     Means for Solving Problem 
     To solve the problems above and achieve an object, according to the present invention, a timepiece component constituting a timepiece, includes a base material formed using a nonconductive first material as a main component; an intermediate film provided on at least a portion of a surface of the base material; and a buffer film stacked on the intermediate film and mainly composed of a second material having a tenacity higher than that of the first material. 
     In the timepiece component, the first material is silicon. 
     In the timepiece component, the second material is a resin. 
     In the timepiece component, the base material includes a stepped portion on an outer surface, and the intermediate film is provided at a position covering at least the stepped portion. 
     In the timepiece component, the timepiece component is a hairspring constituting a speed governing mechanism of a driving unit of a mechanical timepiece. 
     In the timepiece component, the timepiece component is one of a gear, an anchor, and a balance wheel constituting a driving unit of a timepiece and having a hole into which another member is fitted. 
     According to another aspect of the present invention, a method of manufacturing a timepiece component, includes forming a base material into a shape of a timepiece component by etching a substrate formed using a nonconductive first material as a main component; forming an intermediate film on at least a portion of a surface of the base material; and forming a buffer film by stacking on the intermediate film, a material mainly composed of a second material having a tenacity higher than that of the first material. 
     The method further includes forming a stepped portion on the surface of the base material, where the forming of the intermediate film is performed after the forming of the stepped portion. 
     In the method, the forming of the buffer film includes forming the buffer film by applying a predetermined voltage to the intermediate film after the base material having the intermediate film formed thereon is immersed in a predetermined electrodeposition liquid. 
     Effect of the Invention 
     The timepiece component and the method of manufacturing a timepiece component according to the present invention provides an effect of being highly accurate in terms of manufacturing while enabling a weight reduction and resistance to breaking, and exhibiting high strength even when an external force is applied. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an explanatory view of a drive mechanism of a mechanical timepiece; 
         FIG. 2  is an explanatory view of a structure of a hairspring of a first embodiment according to the present invention; 
         FIG. 3  is an explanatory view of a cross-section taken along A-A′ in  FIG. 2 ; 
         FIG. 4  is an explanatory view (part  1 ) of a method of manufacturing the hairspring of the first embodiment according to the present invention; 
         FIG. 5  is an explanatory view (part  2 ) of the method of manufacturing the hairspring of the first embodiment according to the present invention; 
         FIG. 6  is an explanatory view (part  3 ) of the method of manufacturing the hairspring of the first embodiment according to the present invention; 
         FIG. 7  is an explanatory view (part  4 ) of the method of manufacturing the hairspring of the first embodiment according to the present invention; 
         FIG. 8  is an explanatory view (part  5 ) of the method of manufacturing the hairspring of the first embodiment according to the present invention; 
         FIG. 9  is an explanatory view (part  6 ) of the method of manufacturing the hairspring of the first embodiment according to the present invention; 
         FIG. 10  is an explanatory view of a structure of the hairspring of a second embodiment according to the present invention; 
         FIG. 11  is an explanatory view of a cross-section taken along B-B′ in  FIG. 10 ; 
         FIG. 12  is an explanatory view (part  1 ) of the method of manufacturing the hair spring of the second embodiment according to the present invention; 
         FIG. 13  is an explanatory view (part  2 ) of the method of manufacturing the hair spring of the second embodiment according to the present invention; 
         FIG. 14  is an explanatory view of a structure of the hairspring according to a third embodiment of the present invention; 
         FIG. 15  is an explanatory view of a cross-section taken along C-C′ in  FIG. 14 ; 
         FIG. 16  is an explanatory view (part  1 ) of the method of manufacturing the hairspring of the third embodiment according to the present invention; 
         FIG. 17  is an explanatory view (part  2 ) of the method of manufacturing the hairspring of the third embodiment according to the present invention; 
         FIG. 18  is an explanatory view (part  3 ) of the method of manufacturing the hairspring of the third embodiment according to the present invention; 
         FIG. 19  is an explanatory view (part  4 ) of the method of manufacturing the hairspring of the third embodiment according to the present invention; 
         FIG. 20  is an explanatory view (part  5 ) of the method of manufacturing the hairspring of the third embodiment according to the present invention; 
         FIG. 21  is an explanatory view (part  6 ) of the method of manufacturing the hairspring of the third embodiment according to the present invention; 
         FIG. 22  is an explanatory view (part  7 ) of the method of manufacturing the hairspring of the third embodiment according to the present invention; 
         FIG. 23  is an explanatory view (part  8 ) of the method of manufacturing the hairspring of the third embodiment according to the present invention; 
         FIG. 24  is an explanatory view (part  9 ) of the method of manufacturing the hairspring of the third embodiment according to the present invention; 
         FIG. 25  is an explanatory view (part  10 ) of the method of manufacturing the hairspring of the third embodiment according to the present invention; 
         FIG. 26  is an explanatory view (part  11 ) of the method of manufacturing the hairspring of the third embodiment according to the present invention; 
         FIG. 27  is an explanatory view (part  1 ) of the method of manufacturing the hairspring of a fourth embodiment according to the present invention; 
         FIG. 28  is an explanatory view (part  2 ) of the method of manufacturing the hairspring of the fourth embodiment according to the present invention; 
         FIG. 29  is an explanatory view (part  3 ) of the method of manufacturing the hairspring of the fourth embodiment according to the present invention; 
         FIG. 30  is an explanatory view (part  4 ) of the method of manufacturing the hairspring of the fourth embodiment according to the present invention; 
         FIG. 31  is an explanatory view of a structure of an anchor of a fifth embodiment; 
         FIG. 32  is an explanatory view of a cross-section taken along D-D′ in  FIG. 31 ; 
         FIG. 33  is an explanatory view of a structure of a gear of a sixth embodiment; 
         FIG. 34  is an explanatory view (part  1 ) of an electret of the sixth a seventh embodiment according to the present invention; 
         FIG. 35  is an explanatory view (part  2 ) of the electret of the sixth seventh embodiment according to the present invention; 
         FIG. 36  is an explanatory view (part  1 ) of a portion of a drive mechanism in a mechanical timepiece; and 
         FIG. 37  is an explanatory view (part  2 ) of a portion of a drive mechanism in a mechanical timepiece. 
     
    
    
     BEST MODE(S) FOR CARRYING OUT THE INVENTION 
     Embodiments of a timepiece component and a method of manufacturing a timepiece component according to the present invention will be described in detail with reference to the accompanying drawings. 
     First Embodiment 
     (Drive Mechanism of Mechanical Timepiece) 
     First, a drive mechanism of a mechanical timepiece will be described as a drive mechanism of a timepiece incorporating a timepiece component of a first embodiment according to the present invention manufactured by a manufacturing method of the first embodiment according to the present invention.  FIG. 1  is an explanatory view of a drive mechanism of a mechanical timepiece.  FIG. 1  depicts the drive mechanism of the mechanical timepiece incorporating the timepiece component of the first embodiment according to the present invention manufactured by the manufacturing method of the first embodiment according to the present invention. 
     In  FIG. 1 , a drive mechanism  101  of the mechanical timepiece incorporating the timepiece component manufactured by the manufacturing method of the first embodiment according to the present invention includes a barrel  102 , an escapement  103 , a speed governing mechanism (balance)  104 , a train wheel  8  (drive train wheel)  105 , etc. The barrel  102  houses a power mainspring not depicted inside a box forming a thin cylindrical shaped. A gear called a barrel wheel is provided on an outer circumferential portion of the barrel  102  and meshes with a wheel and pinion constituting the train wheel  105 . 
     The power mainspring is an elongated thin metal sheet in a wound state and is housed in the barrel  102 . An end portion at the center of the power mainspring (an end portion located on the inner circumferential side in the wound state) is attached to a center axis (barrel arbor) of the barrel  102 . An outer end portion (an end portion located on the outer circumferential side in the wound state) of the power mainspring is attached to an inner surface of the barrel  102 . 
     The escapement  103  is made up of an escape wheel  106  and an anchor  107 . The escape wheel  106  is a gear including key-shaped teeth, and the teeth of the escape wheel  106  mesh with the anchor  107 . The anchor  107  converts the rotary motion of the escape wheel  106  into reciprocating motion by meshing with the teeth of the escape wheel  106 . 
     The balance  104  is made up of a hairspring  108 , a balance wheel  109 , etc. The hairspring  108  and the balance wheel  109  are coupled by a balance staff  109   a  provided at the center of the balance wheel  109 . The hairspring  108  is an elongated member in a wound state and has a spiral shape (see  FIG. 2 ). The hairspring  108  is designed to exhibit high isochronism in a state of being incorporated in the mechanical timepiece to constitute the drive mechanism  101   
     The balance  104  may regularly reciprocate according to expansion and contraction due to a spring force of the hairspring  108 . The balance wheel  109  forms a ring shape and adjusts/controls the repetitive motion from the anchor  107  to keep vibration at a constant speed. The balance wheel  109  is provided with arms extending radially from the balance staff  109   a  inside the ring shape formed by the balance wheel  109 . 
     The train wheel  105  is provided between the barrel  102  and the escape wheel  106  and is made up of multiple gears meshing with each other. For example, the train wheel  105  is made up of a center wheel and pinion  110 , a third wheel and pinion  111 , a fourth wheel and pinion  112 , etc. The barrel wheel of the barrel  102  meshes with the center wheel and pinion  110 . A second hand  113  is mounted on the fourth wheel and pinion  112 , and a minute hand  114  is mounted on the center wheel and pinion  110 . In  FIG. 1 , an hour hand, a bottom plate supporting the gears, etc. are not depicted. 
     In the drive mechanism  101 , the center of the power mainspring is fixed to the center (barrel arbor) of the barrel  102  so as not to rotate backward and the outer end portion of the power mainspring is fixed to the inner circumferential surface of the barrel, so that when the power mainspring wound around the center (barrel arbor) of the barrel  102  attempts to return to an original state, the barrel  102  is urged by the outer end portion of the power mainspring attempting to loosen in the same direction as the wound-up direction and rotates in the same direction as the loosening direction of the wound-up mainspring. The rotation of the barrel  102  is sequentially transmitted through the center wheel and pinion  110 , the third wheel and pinion  111 , and the fourth wheel and pinion  112  and is transmitted from the fourth wheel and pinion  112  to the escape wheel  106 . 
     Since the escape wheel  106  is meshed with the anchor  107 , when the escape wheel  106  rotates, a tooth (impact surface) of the escape wheel  106  pushes up an entry pallet of the anchor  107  and, as a result, the balance  104  is rotated by a tip of the anchor  107  on the balance  104  side. When the balance  104  rotates, an exit pallet of the anchor  107  immediately stops the escape wheel  106 . When the balance  104  rotates backward due to the force of the hairspring  108 , the entry pallet of the anchor  107  is released and the escape wheel  106  rotates again. 
     In this way, the speed governing mechanism  104  causes the balance  104  to repeat the regular reciprocating rotary motion according to the expansion and contraction of the isochronous hairspring  108 , and the escapement  103  continuously gives the force for reciprocation to the balance  104  and rotates the gears in the train wheel  105  at constant speed according to the regular vibrations from the balance  104 . The escape wheel  106 , the anchor  107 , and the balance  104  constitute a speed governing mechanism converting the reciprocating motion of the balance  104  into the rotary motion. 
     (Structure of Hairspring  108 ) 
       FIG. 2  is an explanatory view of the structure of the hairspring  108  of the first embodiment according to the present invention.  FIG. 2  depicts a plane view of the hairspring  108  of the first embodiment in a direction of an arrow X in  FIG. 1 . In particular,  FIG. 2  depicts the hairspring  108  in a state of a planar view in an axial direction of a rotating shaft body such as the gears  110  to  112  constituting the train wheel  105 . In the following description, the hairspring  108  of the first embodiment will be denoted by reference character  108   a.    
     In  FIG. 2 , the hairspring  108   a  is made up of a collet  3 , a spring unit  2 , and a stud  4 . The collet  3  is included as the collet  3  having a through-hole  31  at the center portion for fitting a balance staff that is a rotating shaft body. The spring unit  2  has a coil shape designed to be wound around the collet  3  with the through-hole  31  of the collet  3  located at the center. The stud  4  is connected to the end of winding of the spring unit  2 . The spring unit  2  is connected to the collet  3  via a connection portion  32  at a winding start portion. 
       FIG. 3  is an explanatory view of a cross-section taken along A-A′ in  FIG. 2 .  FIG. 3  is an enlarged view of four rounding portions of the spring unit  2 . As depicted in  FIG. 3 , the spring unit  2  has a single structure formed by connecting spring arms  201   a ,  201   b ,  201   c , and  201   d  from an inner circumference. 
     In the spring arm  201 , the spring arm  201   a  is located at the innermost circumferential side of the spring unit  2  with the spring arm  201   b  and spring arm  201   c  located in order from the inner circumferential side toward the outer circumferential side, and the spring arm  201   d  is located on the outermost circumferential side of the spring unit  2 . Each of the spring arms  201   a  to  201   d  may be 50 μm in width and 100 μm in height, for example. 
     The spring arms  201   a  to  201   d  are made up of intermediate films  51   a ,  51   b ,  51   c ,  51   d  and buffer films  21   a ,  21   b ,  21   c ,  21   d  sequentially stacked on surfaces of base materials  11   a ,  11   b ,  11   c ,  11   d . The buffer films  21   a  to  21   d  are formed on the outermost surface of the hairspring  108   a . As described above, the spring arms  201   a  to  201   d  form a single integrated structure, and the base materials  11   a  to  11   d  therefore form a single structure as well. Similarly, the intermediate films  51   a  to  51   d  also form a single structure, and the buffer films  21   a  to  21   d  form a single structure as well. 
     The base materials  11   a  to  11   d  are formed by using a first material. For the first material, for example, a material mainly composed of quartz, ceramics, silicon, silicon oxide, etc. may be used. By using silicon as the first material for forming the base materials  11   a  to  11   d , the hairspring  108   a  may be reduced in weight. 
     Additionally, by using silicon as the first material  11  for forming the base materials  11   a  to  11   d , favorable processability may be ensured in manufacturing of the hairspring  108   a . For example, by using silicon as the first material  11  for forming the base materials  11 , the hairspring  108   a  may be manufactured by using a Deep RIE technique. 
     The Deep RIE technique is generally frequently used as a semiconductor manufacturing technique. The Deep RIE technique is a kind of reactive ion etching that is a kind of dry etching processing, and is widely known as a technique capable of microfabrication with high precision. By processing a silicon substrate through dry etching using the Deep RIE technique, the hairspring  108   a  may be manufactured with high precision. By manufacturing the hairspring  108   a  by using the Deep RIE technique, the spring unit  2 , the collet  3 , and the stud  4  may integrally be formed. 
     The intermediate films  51   a  to  51   d  are formed by using a material having a tenacity higher than that of the first material forming the base materials  11   a  to  11   d . The tenacity indicates a property of being hard to break against an external pressure, or so-called “toughness”. Materials having high tenacity exhibit favorable toughness. For example, the intermediate films  51   a  to  51   d  may be formed by using, for example, silicon oxide (SiO 2 ), alumina (aluminum oxide: Al 2 O 3 ), or DLC (Diamond-Like Carbon). 
     The intermediate films  51   a  to  51   d  formed of silicon oxide include a natural oxide film formed of silicon oxide formed by exposing silicon to the atmosphere. DLC is mainly composed of carbon (C) isotopes and hydrocarbons and forms an amorphous structure. DLC is a hard film and includes those having a conductivity imparted thereto by various methods such as implanting plasma ions and adding metal elements by sputtering in recent years. 
     The intermediate films  51   a  to  51   d  may have a conductivity and may be formed by using a metal material such as copper (Cu), gold (Au), nickel (Ni), and titanium (Ti), for example. In particular, the intermediate films  51   a  to  51   d  may be formed by using an alloy acquired by mixing multiple materials. 
     For example, the intermediate films  51   a  to  51   d  may be formed, for example, by forming films of copper (Cu) with a thickness of 0.2 μm on the surfaces of the base materials  11   a  to  11   d . Alternatively, for example, the intermediate films  51   a  to  51   d  may be achieved as natural oxide films formed by exposing silicon forming the base materials  11   a  to  11   d  to the atmosphere. 
     The material forming the intermediate films  51   a  to  51   d  may be set appropriately depending on the hardness required for the timepiece component such as the hairspring  108   a , for example. The hardness required for the timepiece component such as the hairspring  108   a  may be set arbitrarily depending on the specifications, the usage environment, the cost of manufacturing of the mechanical timepiece, for example. The hardness required for the timepiece component such as the hairspring  108   a  may be adjusted by not only the material of the intermediate films  51   a  to  51   d  but also the film thickness of the intermediate films  51   a  to  51   d , for example. 
     For example, when a high hardness is required for the timepiece component such as the hairspring  108   a , titanium (Ti) may be used that is a metal harder than copper (Cu) and gold (Au). On the other hand, for example, when flexibility and ductility are required for the clock component such as the hairspring  108   a , copper (Cu) or gold (Au) having relatively soft characteristics can be used. Copper (Cu) and gold (Au) may exhibit ductility because of soft characteristics and may therefore deform following the deformation of the hairspring  108   a , so that even when silicon is used for forming the hairspring  108   a , the fragility (brittleness) of the hairspring  108   a  may be reduced. 
     The buffer films  21   a  to  21   d  are mainly composed of a second material. The second material may be achieved by a material having a tenacity higher than that of the first material. For example, if the first material is silicon, the second material may be achieved by a resin having a tenacity higher than that of silicon. Materials usable as the second material include, for example, an acrylic resin, an epoxy resin, and a para-xylylene-based polymer that is a polymer synthetic material. 
     Various improvements have been made in acrylic resins in recent years, resulting in the development of an acrylic resin called electrodeposition resist that may be formed in to a film having a constant thickness by an electrodeposition method and that may be patterned. By using such an electrodeposition resist made of an acrylic resin, the buffer films  21   a  to  21   d  having a constant (uniform) film thickness may be provided on a surface of a timepiece component having a precise and complicated shape such as the hairspring  108   a.    
     The hairspring  108   a  required to extend and contract in a constant cycle becomes unbalanced and eccentric if the thickness of the buffer films  21   a  to  21   d  provided on the surface of the hairspring  108   a  is not uniform. By using the acrylic resin called electrodeposition resist, the buffer films  21   a  to  21   d  having a constant (uniform) film thickness may be provided, so that the hairspring  108   a  may operate correctly. As described above, the electrodeposition resist made of an acrylic resin is suitable for a material of timepiece components having a precise and complicated shape, or particularly, the buffer films  21   a  to  21   d  etc. used for the hairspring  108   a  extending and contracting for operation. 
     Additionally, in not only the hairspring  108   a  but also other timepiece components, if a portion with uneven thickness such as a so-called “buffer film gathering” exists on the surfaces of the buffer films  21   a  to  21   d  or the buffer films  21   a  to  21   d  differs in film thickness depending on a location, a trouble may occur such as rubbing against another structure at the time of movement and generating inconsistency in operation, for example. If the buffer films  21   a  to  21   d  protrude from the surfaces of the base materials  11   a  to  11   d , the outer shape of the timepiece component may become different from designed dimensions. In such a case, the shape is not formed as designed, resulting in a timepiece component lacking a predetermined performance (a defective product). 
     In this regard, by using the acrylic resin called electrodeposition resist as the second material to form the buffer films  21   a  to  21   d  with the electrodeposition method, the buffer films  21   a  to  21   d  having a constant (uniform) film thickness can be formed on the surfaces of the base materials  11   a  to  11   d , so that the trouble as described can be avoided. The buffer films  21   a  to  21   d  are formed to be 5 μm in thickness, for example. 
     When the buffer films  21   a  to  21   d  are formed with the electrodeposition method, the intermediate films  51   a  to  51   d  can be used as electrodes to which a voltage is applied during electrodeposition. In the electrodeposition of an object by the electrodeposition method, a material to be electrodeposited (e.g., an acrylic resin) is formed on an upper portion (surface) of an underlying electrode. Therefore, by providing the intermediate films  51   a  to  51   d  having shapes matched to the shapes of the buffer films  21   a  to  21   d  desired to be formed, the buffer films  21   a  to  21   d  reflecting the shapes of the underlying intermediate films  51   a  to  51   d  may easily be formed. 
     (Method of Manufacturing Hairspring  108   a ) 
     A method of manufacturing the hairspring  108   a  will be described as a method of manufacturing a timepiece component of the first embodiment according to the present invention.  FIGS. 4, 5, 6, 7, 8, and 9  are explanatory views of the method of manufacturing the hairspring  108   a  of the first embodiment according to the present invention.  FIGS. 4 to 6  depict steps of forming the base materials  11   a  to  11   d  in the hairspring  108   a .  FIGS. 7 to 9  depict steps of sequentially forming metal films and buffer films on the surfaces of the base materials  11   a  to  11   d .  FIGS. 4 to 9  depict the positions corresponding to  FIG. 3  described above. 
     For manufacturing the hairspring  108   a , first, a silicon substrate  60  is prepared. The silicon substrate  60  has an area and a thickness sized such that at least the hairspring  108   a  may be taken out. Considering the productivity of the hairspring, the silicon substrate  60  is preferably sized such that a number of the hairsprings  108   a  can be taken out. 
     Subsequently, as depicted in  FIG. 4 , a mask layer  90   a  is formed on a front surface of the silicon substrate  60 , and a mask layer  90   b  is formed as a film on a back surface of the silicon substrate  60 . The mask layers  90   a ,  90   b  function as protective films in processing using the Deep RIE technique performed at the subsequent step. The mask layers  90   a ,  90   b  are preferably formed of silicon oxide (SiO 2 ) having an etching rate slower than silicon. If silicon oxide is used, the mask layers  90   a ,  90   b  may be formed by using, for example, a known vapor phase growth technique or a film formation technique represented by a CVD method. The mask layers  90   a ,  90   b  may be formed by growing silicon oxide to a film thickness of 1 μm on the front surface of the silicon substrate  60 , for example. 
     Subsequently, as depicted in  FIG. 5 , a mask layer  91   a  is formed on the front surface of the silicon substrate  60 . The mask layer  91   a  may be formed by patterning the mask layer  90   a  into the shape of the hairspring  108   a . The mask layer  91   a  may be patterned into the shape of the hairspring  108   a  by processing using a photolithography method widely known in general. 
     Subsequently, as depicted in  FIG. 6 , the silicon substrate  60  is processed into the shape of the hairspring  108   a . The silicon substrate  60  may be processed by performing dry etching through the mask layer  91   a  with the Deep RIE technique using a mixed gas (SF 6 +C 4 F 8 )  300  of SF 6  and C 4 F 8 , for example. 
     The silicon substrate  60  can be processed into a shape of an hairspring having a predetermined width by performing dry etching through the mask layer  91   a . The silicon substrate  60  may be processed to a predetermined height (depth) by managing the processing time of the dry etching. By the dry etching through the mask layer  91   a  to the silicon substrate  60 , the base materials  11   a  to  11   d  serving as the spring arms  201   a  to  201   d  are formed as denoted by reference characters  11   a  to  11   d  in  FIG. 6 . 
     Subsequently, as depicted in  FIG. 7 , the mask layer  90   b  and the mask layer  91   a  are removed from the processed silicon substrate  60  to expose the base materials  11   a  to  11   d  of the hairspring  108   a . The mask layer  90   b  and the mask layer  91   a  may be removed, for example, by immersing the silicon substrate  60  dry-etched as described above in a known etchant mainly composed of hydrofluoric acid. 
     Subsequently, as depicted in  FIG. 8 , the intermediate films  51   a  to  51   d  are formed on the surfaces of the base materials  11   a  to  11   d . The intermediate films  51   a  to  51   d  are formed on the entire surfaces of the base materials  11   a  to  11   d , for example. As described above, for example, copper (Cu), gold (Au), nickel (Ni), etc. may be used as the material forming the intermediate films  51   a  to  51   d.    
     The intermediate films  51   a  to  51   d  using copper (Cu), gold (Au), nickel (Ni), etc. are formed, for example, by using a sputtering method that is a kind of a vacuum film formation method to be 0.2 μm in thickness, for example. Alternatively, the intermediate films  51   a  to  51   d  may be achieved by natural oxide films (silicon oxide) formed on the surface of the silicon substrate  60  by exposing the silicon substrate  60  to the atmosphere, for example. 
     The intermediate films  51   a  to  51   d  serve as a foundation when the buffer films  21   a  to  21   d  are provided at the subsequent step. Additionally, the intermediate films  51   a  to  51   d  using copper (Cu), gold (Au), nickel (Ni), etc. act as electrodes when the buffer films  21   a  to  21   d  are formed by using an electrodeposition method described later. In the case of causing the buffer films  21   a  to  21   d  to act as electrodes, preferably, the intermediate films  51   a  to  51   d  are formed by using a material having a low electrical resistance. 
     Subsequently, as depicted in  FIG. 9 , the buffer films  21   a  to  21   d  are formed on the surfaces of the intermediate films  51   a  to  51   d . As described above, the buffer films  21   a  to  21   d  are provided so as to mitigate external forces applied to the hairspring  108   a  and protect the base materials  11   a  to  11   d  made of a brittle material such as silicon from destruction. Therefore, a material having a tenacity higher than that of the first material constituting the base materials  11   a  to  11   d  is used for the second material constituting the buffer films  21   a  to  21   d.    
     The second material forming the buffer films  21   a  to  21   d  may be selected depending on the hardness required for a timepiece component such as the hairspring  108   a  and the material forming the intermediate films  51   a  to  51   d . In other words, the material forming the intermediate films  51   a  to  51   d  may be selected depending on the second material forming the buffer films  21   a  to  21   d.    
     For example, when the intermediate films  51   a  to  51   d  are formed by using copper (Cu), the second material constituting the buffer films  21   a  to  21   d  may b be preferably achieved by using an acrylic resin or an epoxy resin. The buffer films  21   a  to  21   d  may be formed easily by using various known techniques such as a technique of spraying an acrylic resin or an epoxy resin (e.g., sputtering) or dropping a liquefied resin (e.g., spin coating) onto the silicon substrate  60  in a state of being rotated by a spin coating apparatus, for example, and a technique of immersing the substrate in a liquid tank containing a liquefied resin and then removing the substrate to form the films. 
     For example, in the case of forming the buffering films  21   a  to  21   d  by using a technique of dropping a liquefied resin for forming the films, first, a dispenser (not depicted) filled with a predetermined liquefied resin is prepared. Subsequently, for example, while a movable table (not depicted) with the hairspring  108   a  placed thereon is moved in a predetermined direction, the resin of the buffer films  21   a  to  21   d  is dropped from this dispenser. In this case, the resin is dropped so as not to protrude from the intermediate films  51   a  to  51   d  on the surfaces of the spring arms  201   a  to  201   d.    
     Subsequently, a predetermined curing treatment is performed to cure the resin. The curing treatment curing the resin may be achieved by, for example, radiating ultraviolet light for a predetermined time in the case of using an ultraviolet curable resin. Alternatively, the curing treatment may be achieved by, for example, heating for a predetermined time in the case of using a thermosetting resin. As a result, the buffer films  21   a  to  21   d  may be formed on the surfaces of the intermediate films  51   a  to  51   d  formed on the surfaces of the spring arms  201   a  to  201   d.    
     The buffer films  21   a  to  21   d  may also be formed by using an electrodeposition method. In the technique of dropping the resin for forming the buffer films  21   a  to  21   d , the resin may not be formed uniformly in rare cases. In contrast, by using the electrodeposition method, the resin constituting the buffer films  21   a  to  21   d  may be formed into films having a constant thickness, and may be patterned easily, on the surfaces of the intermediate films  51   a  to  51   d . When the buffer films  21   a  to  21   d  are formed by the electrodeposition method, an acrylic resin called electrodeposition resist is used. The electrodeposition method is a widely known film formation method in which a substance precipitated by electrolysis is attached for film formation onto the intermediate films  51   a  to  51   d  to which a voltage is applied. 
     For example, when the buffer films  21   a  to  21   d  are formed by using the electrodeposition method, the intermediate films  51   a  to  51   d  are formed in advance on a predetermined portion of the hairspring  108   a . When the buffer films  21   a  to  21   d  are formed by using the electrodeposition method, preferably, the intermediate films  51   a  to  51   d  are formed by using copper (Cu) having a low electrical resistance, for example. A terminal region (not depicted) electrically connected to the intermediate films  51   a  to  51   d  is formed at the same time as the formation of the intermediate films  51   a  to  51   d . This terminal region is provided in a portion not affecting the shape of the hairspring  108   a.    
     Subsequently, the silicon substrate  60  with the intermediate films  51   a  to  51   d  and the terminal region formed is immersed in a state of being fixed by a known holding device into a liquid tank filled with an electrodeposition liquid containing the electrodeposition resist. In this case, a probe, etc. are preliminarily brought into contact with the terminal region electrically connected to the intermediate films  51   a  to  51   d . The probe, etc. are connected to a predetermined power supply unit so that a predetermined voltage may be applied to the intermediate films  51   a  to  51   d.    
     When a predetermined voltage is applied to the intermediate films  51   a  to  51   d  immersed in the electrodeposition liquid tank with the probe, etc. brought into contact with the terminal region, the electrodeposition resist precipitated by electrolysis in the liquid tank is attached to the surfaces of the intermediate films  51   a  to  51   d . The voltage is applied until the electrodeposition resist reaches a predetermined film thickness. Although not particularly limited hereto, the electrodeposition resist is formed into a film having a thickness of 5 μm. The film thickness of the electrodeposition resist may be freely set in view of specifications, etc. of the mechanical timepiece. Therefore, when the buffer films  21   a  to  21   d  are formed by using the electrodeposition method, the film thickness of the electrodeposition resist may be adjusted easily by managing the time of application of the voltage. 
     Subsequently, the application of the voltage is terminated and the silicon substrate  60  is taken out from the liquid tank. As a result, the buffer films  21   a  to  21   d  reflecting the shapes of the intermediate films  51   a  to  51   d  may be formed on the surfaces of the intermediate films  51   a  to  51   d  to have a constant film thickness. By using the electrodeposition method, the buffer films  21   a  to  21   d  may be formed without significantly varying the shape of the hairspring  108   a  before and after forming the buffer films  21   a  to  21   d.    
     For example, when the intermediate films  51   a  to  51   d  are achieved by natural oxide films (silicon oxide), the second material constituting the buffer films  21   a  to  21   d  may be preferably achieved by a resin material such as a para-xylylene-based polymer. The para-xylylene-based polymer is a polymer of an organic compound, para-xylylene, and can be formed into a thin film shape by causing a polymerization reaction on the surface of the hairspring  108   a.    
     The para-xylylene-based polymer has a high conformal coatability. Therefore, by using the para-xylylene-based polymer, the buffer films  21   a  to  21   d  having a uniform film thickness without a pinhole may be formed even when a component has a fine complicated shape due to groove/hole/edge portions as in the case of a timepiece component such as the hairspring  108   a  used in a wristwatch, for example. The buffer films  21   a  to  21   d  made of the para-xylylene-based polymer may be formed by using a gas phase vapor deposition polymerization method that is a kind of chemical vapor deposition (CVD), for example. 
     With the manufacturing method as described above, the hairspring  108   a  with the buffer films  21   a  to  21   d  formed on the entire surface may be manufactured. In the hairspring  108   a  that is the timepiece component of the first embodiment, the base materials  11   a  to  11   d  are main members forming the shape of the timepiece component and are made of the first material (e.g., silicon) that is a nonconductive material, and the intermediate films  51   a  to  51   d  are included at least partially on the surfaces of the base materials  11   a  to  11   d . The buffer films  21   a  to  21   d  made of the second material having a tenacity higher than that of the first material are provided on the surfaces of the intermediate films  51   a  to  51   d.    
     As described above, the timepiece component of the first embodiment includes the base materials  11   a  to  11   d  formed by using silicon. Therefore, microfabrication may be performed with high accuracy by etching processing using the Deep RIE technique, so that a timepiece component forming a fine complicated shape may be manufactured with high precision and reduced variations in processing accuracy. 
     Moreover, the timepiece component of the first embodiment includes at least partially on the surfaces of the base materials  11   a  to  11   d  the intermediate films  51   a  to  51   d  formed by using a material having a tenacity higher than that of silicon forming the base materials  11   a  to  11   d . Therefore, the timepiece component of the first embodiment may reduce the fragility of silicon to achieve a robust timepiece component even when silicon is used for forming the base materials  11   a  to  11   d.    
     Furthermore, the timepiece component of the first embodiment includes the buffer films  21   a  to  21   d  having a high tenacity on the surfaces of the intermediate films  51   a  to  51   d . Therefore, the timepiece component of the first embodiment has the buffer films  21   a  to  21   d  acting as a cushion and may mitigate the impact with the buffer films  21   a  to  21   d  even when the timepiece component comes into contact with another structure. Additionally, inclusion of the buffer films  21   a  to  21   d  enables the timepiece component of the first embodiment to prevent cracking and chipping due to stress concentration at a corner, etc. Therefore, the durability of the timepiece component may be improved. 
     As described above, the timepiece component of the first embodiment may reduce the fragility of silicon with the intermediate films  51   a  to  51   d  provided at least partially on the surfaces of the base materials  11   a  to  11   d  formed by using a silicon material and may mitigate external forces applied to the timepiece component by the buffer films  21   a  to  21   d  having a high tenacity provided on the surfaces of the intermediate films  51   a  to  51   d  so as to prevent cracking or chipping due to stress concentration at corners, etc. 
     According to the timepiece component of the first embodiment, since two different types of films are included as the intermediate films  51   a  to  51   d  and the buffer films  21   a  to  21   d , a timepiece component may be achieved that is robust and resistant to breakage even when a contact with another structure or stress concentration occurs due to an impact. 
     According to the timepiece component of the first embodiment 1, the intermediate films  51   a  to  51   d  may be formed by using a material having a conductivity such as a metal material so as to use the intermediate films  51   a  to  51   d  as electrodes. In this case, the buffer films  21   a  to  21   d  may be formed by using the electrodeposition method, and the use of the electrodeposition method enables the formation of the buffer films  21   a  to  21   d  having a constant film thickness and a high coatability to the foundation (e.g., the intermediate films  51   a  to  51   d ). 
     According to the timepiece component of the first embodiment, even when a metal material is used, the metal material is used as a material forming the intermediate films  51   a  to  51   d  covering the surfaces of the base materials  11   a  to  11   d . Therefore, the film thickness of the intermediate films  51   a  to  51   d  is extremely thin with respect to the thickness of the silicon. As a result, the timepiece component of the first embodiment does not adversely affect the excellent temperature characteristics of silicon. 
     Thus, even when the intermediate films  51   a  to  51   d  are formed by using a metal material having inferior temperature characteristics for the timepiece component as compared to the silicon forming the base materials  11   a  to  11   d , the temperature characteristics of the first material such as silicon is not adversely affected unlike a metal plate formed by rolling, etc. of metal having a predetermined plate shape. As a result, the timepiece component of the first embodiment may exert the excellent temperature characteristics of silicon and may exhibit high strength. 
     As described above, according to the timepiece component of the first embodiment, the hairspring  108   a  highly accurate in terms of manufacturing may be reduced in weight by using the first material mainly composed of silicon, etc. for forming the base materials  11   a  to  11   d  and since the intermediate films  51   a  to  51   d  and the buffer films  21   a  to  21   d  are provided, the timepiece component is resistant to breakage and may exhibit high strength even when an external impact is applied. 
     Second Embodiment 
     A hairspring will be described as a timepiece component of a second embodiment according to the present invention manufactured by a manufacturing method of the second embodiment according to the present invention. In the second embodiment, portions identical to as those of the first embodiment described above are denoted by the same reference characters used in the first embodiment and will not be described. In the description of the second embodiment, the hairspring  108  will be denoted by reference character  108   b.    
       FIG. 10  is an explanatory view of the structure of the hairspring  108   b  of the second embodiment according to the present invention.  FIG. 10  depicts a plane view of the hairspring  108   b  of the second embodiment in a direction of the arrow X of  FIG. 1 .  FIG. 11  is an explanatory view of a cross-section taken along B-B′ in  FIG. 10 . In  FIGS. 10 and 11 , the hairspring  108   b  of the second embodiment includes the spring unit  2  forming a single structure acquired by connecting spring arms  202   a ,  202   b ,  202   c ,  202   d  from an inner circumference. 
     The spring arms  202   a  to  202   d  may be, for example, 50 μm in width and 100 μm in height as is the case in the first embodiment. Both end portions of the spring unit  2  are formed by overlapping intermediate films  52   a ,  52   b ,  52   c ,  52   d  and buffer films  22   a ,  22   b ,  22   c ,  22   d  as is the case in the first embodiment. In the spring arms  202   a  to  202   d , for example, the base materials  11   a  to  11   d  may be formed by using silicon as is the case in the first embodiment. 
     In the spring arms  202   a  to  202   d , the intermediate films  52   a  to  52   d  are provided to cover four corners  1100  of the base materials  11   a  to  11   d  made of the first material. The intermediate films  52   a  to  52   d  can be formed by using the same material as the first embodiment in the same way as the manufacturing method of the first embodiment. For example, as is the case in the first embodiment, the film thickness of the intermediate films  52   a  to  52   d  can be 0.2 μm. 
     In the spring arms  202   a  to  202   d , the buffer films  22   a  to  22   d  are provided as upper layers on the intermediate films  52   a  to  52   d . The buffer films  22   a  to  22   d  are formed by using the second material as a main component. Although not particularly limited hereto, the film thickness of the buffer films  22   a  to  22   d  may be 5 μm, for example. The second material may be achieved by, for example, a resin or an electrodeposition resist as is the case in the first embodiment. If the electrodeposition resist is used as the second material, the buffer films  22   a  to  22   d  having a constant film thickness may be formed on the surfaces of the intermediate films  52   a  to  52   d  as is the case in the first embodiment. 
     The electrodeposition resist is the same as the photoresist and, therefore, by combining known photolithography and etching techniques, the buffer films  22   a  to  22   d  patterned in a predetermined shape may be formed only at the four corners  1100  of the base materials  11   a  to  11   d  in the spring arms  202   a  to  202   d.    
     If some impact is applied to the hairspring  108   b , the stress concentrates at the corners  1100 . Therefore, when the hairspring  108   b  is formed by using a brittle material such as silicon, the corners  1100  may possibly chip or crack due to the effects of the impact. In this regard, as depicted in  FIG. 11 , the hairspring  108  of the second embodiment has the intermediate films  52   a  to  52   d  and the buffer films  22   a  to  22   d  with high tenacity provided at the corners  1100  of the hairspring  108   b  at which the stress concentrates, so that an impact applied to the corners  1100  may be mitigated. As a result, the robust hairspring  108   b  may be achieved. 
     (Method of Manufacturing Hairspring  108   b ) 
     A method of manufacturing the hairspring  108   b  will be described as a method of manufacturing a timepiece component of the second embodiment according to the present invention.  FIGS. 12 and 13  are explanatory views of the method of manufacturing the hair spring  108   b  of the second embodiment according to the present invention. For manufacturing the hairspring  108   b , first, as is the case at the steps in  FIGS. 4 to 9  in the first embodiment described above, the intermediate films  52   a  to  52   d  and the buffer films  22   a  to  22   d  are sequentially formed on the surfaces of the base materials  11   a  to  11   d . The second embodiment will be described by taking, as an example, the buffer films  22   a  to  22   d  formed of the electrodeposition resist by using the electrodeposition method. 
     The buffer films  22   a  to  22   d  are patterned into a predetermined shape. As depicted in  FIG. 12 , the buffer films  22   a  to  22   d  are patterned by exposing the buffer films  21   a  to  21   d  made of the electrodeposition resist to an ultraviolet light  600  only in predetermined portions through exposure masks  500 ,  510 . 
     The buffer films  22   a  to  22   d  of the second embodiment may be formed by using, for example, the electrodeposition resist made of a photosensitive material of a type in which an exposed portion is developed and dissolved. In this case, the exposure masks  500 ,  510  used are designed such that a portion to be left as a pattern is not exposed. For example, if it is desired to leave buffer films on the corners  1100  of the hairspring  108   b , the exposure masks  500 ,  510  are shaped such that the ultraviolet light  600  is not applied to the corners  1100 . 
     In patterning the buffer films  22   a  to  22   d , as depicted in  FIG. 12 , the ultraviolet light  600  may be applied to a side surface  80  of the hairspring  108   b  by applying the ultraviolet light  600  in an oblique direction to the hairspring  108   b . In patterning the buffer films  22   a  to  22   d , for example, as depicted in  FIG. 12 , the light is applied at the exposure of 400 mJ/cm 2  by using an exposure device applying the ultraviolet light  600  in an oblique direction to the surfaces of the base materials  11   a  to  11   d.    
     Subsequently, the exposed portions of the buffer films  21   a  to  21   d  made of the electrodeposition resist are removed as depicted in  FIG. 13 . By removing the exposed portions, the buffer films  22   a  to  22   d  patterned only on the corners  1100  of the hairspring  108   b  may be formed. The removal of the exposed portions may be achieved by dissolving the exposed portions by using a known developing solution. For example, the removal of the exposed portions is performed by, for example, developing the portions for 20 minutes by using electrolytic reduction ionized water at 25 degrees C. as the developing solution. 
     Subsequently, the intermediate films  51   a  to  51   d  are etched by using, as a mask, the buffer films  22   a  to  22   d  patterned only on the corners  1100  of the hairspring  108   b . For example, if the intermediate films  51   a  to  51   d  are formed by using copper (Cu), the intermediate films  51   a  to  51   d  may be etched by using a cupric chloride-based etchant. 
     As a result, as depicted in  FIG. 11 , the portions of the intermediate films  51   a  to  51   d  not covered with the buffer films  22   a  to  22   d  are removed by etching, and the intermediate films  52   a  to  52   d  patterned in the same shape as the buffer films  22   a  to  22   d  are formed. When the portions of the intermediate films  51   a  to  51   d  not covered with the buffer films  22   a  to  22   d  are removed by etching, the base materials  11   a  to  11   d  are exposed in the portions corresponding to the portions removed by the etching. In this way, as depicted in  FIG. 11 , the hairspring  108   b  may be manufactured that includes the buffer films  22   a  to  22   d  formed on portions of the surfaces of the base materials  11   a  to  11   d.    
     As described above, in the timepiece component of the second embodiment, by forming the buffer films  21   a  to  21   d  from the electrodeposition resist in advance, the buffer films  21   a  to  21   d  may be processed easily by combining well-known photolithography and etching techniques using a conventional photoresist. As a result, the buffer films  22   a  to  22   d  covering only the four corners  1100  of the base materials  11   a  to  11   d  may easily be formed. 
     In the manufacturing method of the second embodiment, the subsequent processing may be eliminated in the state depicted in  FIG. 13 . In this case, the intermediate films  51   a  to  51   d  remain covering the surfaces of the base materials  11   a  to  11   d . By using such a configuration, the strength of the hairspring  108   b  may be increased. Whether to use the structure depicted in  FIG. 11  or the structure depicted in  FIG. 13  may be selected in view of the specifications and the usage environment of the mechanical timepiece on which the hairspring  108   b  is mounted, for example. 
     Third Embodiment 
     A hairspring will be described as a drive mechanism of a timepiece incorporating a timepiece component of a third embodiment according to the present invention manufactured by a manufacturing method according to the third embodiment according to the present invention. In the third embodiment, portions identical to those of the first and second embodiments described above are denoted by the same reference characters used in the first and second embodiments and will not be described. In the description of the third embodiment, the hairspring  108  will be denoted by reference character  108   c.    
       FIG. 14  is an explanatory view of the structure of the hairspring  108   c  according to the third embodiment of the present invention.  FIG. 14  depicts a plane view of the hairspring  108   c  of the third embodiment in a direction of the arrow X of  FIG. 1 .  FIG. 15  is an explanatory view of a cross-section taken along C-C′ in  FIG. 14 . In  FIGS. 14 and 15 , the hairspring  108   c  of the third embodiment includes the spring unit  2  forming a single structure acquired by connecting spring arms  203   a ,  203   b ,  203   c ,  203   d  from an inner circumference. The spring arms  203   a  to  203   d  may be, for example, 50 μm in width and 100 μm in height as is the case in the first and second embodiments. 
     In the spring unit  2 , end surfaces (flat surfaces)  81  on the front surface side of the base materials  11   a  to  11   d  are provided with groove portions  71   a ,  71   b ,  71   c ,  71   d  recessed in center portions in the width direction from the flat surfaces  81  toward end surfaces (flat surfaces)  82  on the back side of the base materials  11   a  to  11   d . The groove portions  71   a  to  71   d  are recesses having a predetermined width and a predetermined depth. As a result, stepped portions are formed by the flat surfaces  81  and the groove portions  71   a  to  71   d  on the front surface side of the base materials  11   a  to  11   d.    
     Additionally, in the spring unit  2 , the flat surfaces  82  of the base materials  11   a  to  11   d  are provided with groove portions  72   a ,  72   b ,  72   c ,  72   d  recessed in center portions in the width direction from the flat surfaces  82  toward the flat surfaces  81 . The groove portions  72   a  to  72   d  are recesses having a predetermined width and a predetermined depth. As a result, stepped portions are formed by the flat surfaces  82  and the groove portions  72   a  to  72   d  on the back surface side of the base materials  11   a  to  11   d.    
     The groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  are formed to have dimensions of 20 μm in width and 40 μm in depth. The dimensions of the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  are not particularly limited. Intermediate films  53   a ,  53   b ,  53   c ,  53   d  are provided on the inner sides (inner surfaces) of the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d.    
     As is the case in the first and second embodiments, the intermediate films  53   a  to  53   d  are formed by using a material having a tenacity higher than that of the first material forming the base materials  11   a  to  11   d . The intermediate films  53   a  to  53   d  may be formed by using, for example, silicon oxide, alumina, DLC, a metal material, or an alloy acquired by mixing a metal material and other materials. As is the case in the first and second embodiments, the intermediate films  53   a  to  53   d  may be formed to be 0.2 μm in thickness, for example. 
     Buffer films  23   a  to  23   d  are provided on the surfaces of the intermediate films  53   a  to  53   d  as upper layers on the intermediate films  53   a  to  53   d . The buffer films  23   a  to  23   d  are provided to fill the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d . The buffer films  23   a  to  23   d  are formed by using the second material having a tenacity higher than that of the first material, for example, as is the case in the first and second embodiments described above. For example, a resin, an electrodeposition resist, etc. may be used as the second material for the buffer films  23 . By using the electrodeposition resist, the buffer films  23   a  to  23   d  having a constant film thickness (e.g., 5 μm) may be formed as the upper layers on the intermediate films  53   a  to  53   d . In the third embodiment, the buffer films  23   a  to  23   d  are provided to fill the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  as depicted in  FIG. 15 . 
     Resin generally has a density lower than silicon. Therefore, by providing the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  in the base materials  11   a  to  11   d  formed of silicon and by filling the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  with the buffer films  23  formed of a resin as in the case of the hairspring  108   c , the hairspring  108   c  may be reduced in weight by the volume of the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d.    
     Furthermore, by covering the inside of the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  with the intermediate films  53   a  to  53   d  formed by using a metal material, the hairspring  108   c  may be compensated for decreased strength due to provision of the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  (removal of volumes corresponding to the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  from the base materials  11   a  to  11   d ), and the strength of the hairspring  108   c  may be improved. 
     Moreover, by providing the buffer films  23  having a high tenacity as the upper layers on the intermediate films  53   a  to  53   d , the hairspring  108   c  becomes resistant to destruction, and the durability of the hairspring  108   c  may be improved. Additionally, since the intermediate films  53   a  to  53   d  are provided to cover the corners of the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d , even when the hairspring  108   c  is subject to a strong impact, the corners may be prevented from being damaged due to stress concentration. As a result, the robust hairspring  108   c  may be manufactured. 
     By providing the buffer films  23  inside the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d , the resin may be provided inside the base materials  11   a  to  11   d  and as a result, the spring unit  2  may be given an elastic quality so that the spring unit  2  may be made resistant to breakage. 
     In the third embodiment described above, the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  are formed by making concave-shaped recesses in the flat surfaces  81 ,  82  so as to constitute the stepped portions; however, the stepped portions are not limited to those formed of a concave shape. For example, the flat surfaces  81 ,  82  may be projected in a convex shape in the direction opposite to the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  to constitute protrusions, and the intermediate films  53   a  to  53   d  and the buffer films  23  may be formed to cover the protrusions. As a result, the robust hairspring  108   c  may be manufactured. 
     In the description of the third embodiment, the hairspring  108   c  is provided with the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  in both the flat surface  81  and the flat surface  82 ; however, this is not a limitation. The groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  may be provided in only one of the flat surface  81  and the flat surface  82 . 
     (Method of Manufacturing Hairspring  108   c ) 
     A method of manufacturing the hairspring  108   c  will be described as a method of manufacturing the timepiece component of the third embodiment according to the present invention.  FIGS. 16, 17, 18, 19, 20, 21, 22, 23, 14, 25 , and  26  are explanatory views of the method of manufacturing the hairspring  108   c  of the third embodiment according to the present invention. In manufacturing the hairspring  108   c , first, a silicon substrate  61  is prepared. The silicon substrate  61  has an area and a thickness sized such that at least the hairspring  108   c  may be taken out. Considering the productivity of the hairspring, the silicon substrate  61  may be preferably sized such that a number of the hairsprings  108   c  may be taken out. 
     Subsequently, as depicted in  FIG. 16 , a mask layer  92   a  is formed on the front surface side of the flat surface  81  that is the end surface on the front side of the silicon substrate  61 , and a mask layer  92   b  is formed on the back surface side of the flat surface  82  that is the end surface on the back side of the silicon substrate  61 . The mask layers  92   a ,  92   b  have opening patterns formed for forming groove portions in predetermined portions of the hairspring. 
     The mask layers  92   a ,  92   b  function as protective films in processing using the Deep RIE technique performed at the subsequent step. The mask layers  92   a ,  92   b  may be preferably formed of silicon oxide (SiO 2 ) having an etching rate slower than silicon. The mask layers  92   a ,  92   b  may be formed by growing silicon oxide to a film thickness of 1 μm, for example. 
     Subsequently, as depicted in  FIG. 17 , dry etching is performed through the mask layers  92   a ,  92   b  with the Deep RIE technique using the mixed gas (SF 6 +C 4 F 8 )  300  of SF 6  and C 4 F 8  while managing the processing time. As a result, the portions not covered with the mask layers  92   a ,  92   b , i.e., the opening pattern portions opened in a predetermined shape, are subjected to the etching processing. 
     In other words, a silicon substrate  62  is formed that has the groove portions  71   a  to  71   d  formed on the flat surface  81  side and the groove portions  72   a  to  72   d  formed on the flat surface  82  side. Although not particularly limited hereto, the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  are formed to be 20 μm in width and 40 μm in depth, for example. When the silicon substrate  61  is dry-etched by the Deep RIE technique, the etching may be performed twice, separately on respective surfaces as the dry etching performed on the flat surface  81  side and the dry etching performed on the flat surface  82  side. 
     Subsequently, as depicted in  FIG. 18 , the mask layers  92   a ,  92   b  are removed from the silicon substrate  62 . The mask layers  92   a ,  92   b  may be removed, for example, by immersing the silicon substrate  62  in a known etchant mainly composed of hydrofluoric acid. As a result, the mask layer  92   a  provided on the flat surface  81  side and the mask layer  92   b  provided on the flat surface  82  side may be removed simultaneously. 
     Subsequently, as depicted in  FIG. 19 , a mask layer  93   a  is formed on the flat surface  81  on the front surface side of the silicon substrate  62  and the inner walls of the groove portions  71   a  to  71   d . Additionally, as depicted in  FIG. 19 , a mask layer  93   b  is formed on the flat surface  82  on the back surface side of the silicon substrate  62  and the inner walls of the groove portions  72   a  to  72   d.    
     The mask layers  93   a ,  93   b  function as protective films in processing using the Deep RIE technique performed at the subsequent step. The mask layers  93   a ,  93   b  may be preferably formed of silicon oxide (SiO 2 ) having an etching rate slower than that of silicon. The mask layers  93   a ,  93   b  may be formed by growing silicon oxide to a film thickness of 1 μm, for example. 
     Subsequently, as depicted in  FIG. 20 , the mask layer  93   a  is processed to form a mask layer  94   a  patterned into the shape of the hairspring  108   c . When the mask layer  93   a  is processed, the processing is performed by a photolithography method widely known in general. As a result, The mask layer  94   a  patterned into the shape of the hairspring  108   c  may be formed. 
     Subsequently, as depicted in  FIG. 21 , dry etching is performed through the mask layers  94   a ,  93   b  with the Deep RIE technique using the mixed gas (SF 6 +C 4 F 8 )  300  of SF 6  and C 4 F 8  while managing the processing time. As a result, the portions not covered with the mask layer  94   a , i.e., the opening pattern portions opened in a predetermined shape, are subjected to the etching processing, and the silicon substrate  62  is processed into the shapes of base materials  13   a  to  13   d  having a predetermined width and a predetermined height. 
     Subsequently, as depicted in  FIG. 22 , the mask layers  93   b ,  94   a  are removed. The mask layers  93   b ,  94   a  may be removed, for example, by immersing the silicon substrate  62  in a known etchant mainly composed of hydrofluoric acid. As a result, the base materials  13   a  to  13   d  of the hairspring  108   c  as depicted in  FIG. 22  are exposed. The groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  are respectively formed in the base materials  13   a  to  13   d  in the exposed state. 
     Subsequently, as depicted in  FIG. 23 , intermediate films  55   a  to  55   d  are formed to cover the surfaces of the base materials  13   a  to  13   d . The intermediate films  55   a  to  55   d  are also provided inside the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d . The intermediate films  55   a  to  55   d  may be formed by using the various materials described above and may be formed by using copper (Cu), gold (Au), or nickel (Ni), for example. For example, if the intermediate films  53   a  to  53   d  are formed by using copper (Cu), the intermediate films  55   a  to  55   d  may be formed by a sputtering method that is a kind of a vacuum film formation method. The intermediate films  55   a  to  55   d  are formed to be 0.2 μm in thickness, for example. 
     Subsequently, as depicted in  FIG. 24 , buffer films  25   a  to  25   d  are formed as upper layers on the intermediate films  55   a  to  55   d . As described above, the buffer films  25   a  to  25   d  mitigate an impact externally applied to the hairspring  108   c . Therefore, the buffer films  25   a  to  25   d  are formed by using a material having a tenacity higher than that of the first material constituting the base materials  13   a  to  13   d  so as to be suitable for mitigating the impact. In the third embodiment, since the buffer films  25   a  to  25   d  must be processed into a predetermined shape, a material not only suitable for mitigating the impact but also easy to process is selected. 
     For a material having a high tenacity and capable of being patterned (easy to process), for example, an electrodeposition resist made of an acrylic resin used in an electrodeposition method is preferable. Use of the electrodeposition resist made of an acrylic resin enables the buffer films  25   a  to  25   d  having a constant thickness to be formed and the buffer films  25   a  to  25   d  may be favorably patterned. 
     Use of such an electrodeposition resist made of an acrylic resin as the buffer films  25   a  to  25   d , as depicted in  FIG. 24 , enables the buffer films  25   a  to  25   d  made of the electrodeposition resist to be formed easily as upper layers on the intermediate films  55   a  to  55   d  containing copper (Cu) formed on the base materials  13   a  to  13   d  containing silicon. Although not particularly limited hereto, the film thickness of the buffer films  25   a  to  25   d  may be formed to be 5 μm in thickness, for example. 
     Subsequently, as depicted in  FIG. 25 , the buffer films  25   a  to  25   d  made of the electrodeposition resist are exposed to the ultraviolet light  600  only in predetermined portions through exposure masks  520 ,  530 . For the electrodeposition resist used in the third embodiment, as described in the second embodiment 2, for example, the electrodeposition resist may be used that is made of a photosensitive material of a type in which an exposed portion is developed and dissolved. The exposure masks  520 ,  530  are designed such that the buffer films  25   a  to  25   d  in the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  are not exposed to the ultraviolet light  600 . 
     For patterning the buffer films  25   a  to  25   d , as depicted in  FIG. 25 , the ultraviolet light  600  may be applied to the side surface  80  of the hairspring  108   c  by applying the ultraviolet light  600  in an oblique direction to the hairspring  108   c . For patterning the buffer films  25   a  to  25   d , for example, as depicted in  FIG. 25 , the light is applied at the exposure of 400 mJ/cm 2  by using an exposure device applying the ultraviolet light  600  in an oblique direction to the surfaces of the base materials  13   a  to  13   d.    
     Subsequently, the exposed portions of the buffer films  25   a  to  25   d  made of the electrodeposition resist are removed as depicted in  FIG. 26 . By removing the exposed portions, the hairspring  108   c  may be formed that has the buffer films  23   a  to  23   d  remaining only near the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d . The removal of the exposed portions may be achieved by dissolving the exposed portions by using a known developing solution. For example, the removal of the exposed portions is performed by developing the portions for 20 minutes by using electrolytic reduction ionized water at 25 degrees C. as the developing solution as is the case in the second embodiment as described above, for example. 
     Subsequently, the intermediate films  55   a  to  55   d  are etched by using, as a mask, the buffer films  23   a  to  23   d  formed in the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  of the hairspring  108   c . For example, if the intermediate films  55   a  to  55   d  are formed by using copper (Cu), the intermediate films  55   a  to  55   d  may be etched by using a cupric chloride-based etchant. 
     As a result, as depicted in  FIG. 15 , the portions of the intermediate films  53   a  to  53   d  not covered with the buffer films  23   a  to  23   d  are removed by etching, and the intermediate films  53   a  to  53   d  remain in the state of being formed in the portions covered with the buffer films  23   a  to  23   d . When the portions of the intermediate films  53   a  to  53   d  not covered with the buffer films  23   a  to  23   d  are removed by etching, the base materials  13   a  to  13   d  are exposed in the portions corresponding to the portions removed by the etching. In this way, as depicted in  FIG. 15 , the hairspring  108   c  may be manufactured that includes the buffer films  23   a  to  23   d  formed on portions of the surfaces of the base materials  13   a  to  13   d.    
     In the manufacturing method of the third embodiment, the subsequent processing may be eliminated in the state depicted in  FIG. 26 . In this case, the intermediate films  53   a  to  53   d  remain covering the surfaces of the base materials  13   a  to  13   d . By using such a constitution, the strength of the hairspring  108   c  may be increased. Whether to use the structure depicted in  FIG. 15  or the structure depicted in  FIG. 26  may be selected in view of the specifications and the usage environment of the mechanical timepiece on which the hairspring  108   c  is mounted, for example. 
     As depicted in  FIGS. 14 and 15 , the hairspring having the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  may be manufactured easily by the third manufacturing method as described above. Although the buffer films  23   a  to  23   d  are filled inside the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  in the example described in the third embodiment, this is not a limitation. In formation of the buffer films  23   a  to  23   d  by the electrodeposition method, the buffer films  23   a  to  23   d  may be formed with a constant film thickness on the upper portions of the intermediate films  53   a  to  53   d  by managing the formation time, etc. 
     Although the third manufacturing method described above has been described as the manufacturing method in which the buffer films  23   a  to  23   d  are formed in the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  having the concave shape as the stepped portions, even stepped portions having a convex shape (not depicted) may be manufactured by the same manufacturing method. In particular, when the stepped portions are formed, a mask may be patterned to form protrusions on the flat surfaces  81 ,  82 . Portions to be masked and portions to be etched in this case will not be described in detail since this is widely used in the processing of semiconductor devices. 
     Fourth Embodiment 
     (Method of Manufacturing Hairspring) 
     A method of manufacturing a hairspring of a fourth embodiment according to the present invention will be described as a method of manufacturing a timepiece component of the fourth embodiment according to the present invention. In the fourth embodiment, portions identical to those of the first to third embodiments described above are denoted by the same reference characters used in the first to third embodiments and will not be described. In the fourth embodiment, a method of manufacturing the hairspring  108  ( 108   d ) will be described. 
       FIGS. 27, 28, 29, and 30  are explanatory views of the method of manufacturing the hairspring  108   d  of the fourth embodiment according to the present invention. In manufacturing the hairspring  108   d , first, the silicon substrate  61  is prepared. The silicon substrate  61  has an area and a thickness sized such that at least the hairspring  108   d  may be taken out. Considering the productivity of the hairspring, the silicon substrate  61  is preferably sized such that a number of the hairsprings  108   d  may be taken out. 
     Subsequently, as depicted in  FIG. 27 , a first mask layer  95   a  is formed on the front surface side of the flat surface  81  of the silicon substrate  61 , and a mask layer  95   b  is formed on the back surface side of the flat surface  82  of the silicon substrate  61 . The mask layers  95   a ,  95   b  have opening patterns formed in predetermined portions corresponding to the shape of the hairspring  108   d  such that the silicon substrate  61  forms each of the base materials  13   a  to  13   d.    
     As depicted in  FIG. 27 , a second mask layer  97   a  having an opening pattern formed for forming the groove portions  71   a  to  71   d  in predetermined portions of the hairspring  108   d  is formed as an upper layer on the first mask layer  95   a , and a second mask layer  97   b  having an opening pattern formed for forming the groove portions  72   a  to  72   d  in predetermined portions of the hairspring  108   d  is formed as an upper layer on the first mask layer  95   b . In the second mask layers  97   a ,  97   b , opening patterns corresponding to the shape of the hairspring  108   d  are formed at positions corresponding to the opening patterns of the mask layers  95   a ,  95   b.    
     The first mask layers  95   a ,  95   b  function as protective films in processing using the Deep RIE technique performed at the subsequent step. The first mask layers  95   a ,  95   b  are preferably formed of silicon oxide (SiO 2 ) having an etching rate slower than silicon. The first mask layers  95   a ,  95   b  may be formed by growing silicon oxide to a film thickness of 1 μm, for example. 
     The second mask layers  97   a ,  97   b  function as protective films when a groove shape is patterned on the first mask layers  95   a ,  95   b  at the subsequent step. The second mask layers  97   a ,  97   b  are preferably formed of a material having a corrosion resistance with respect to etching of the first mask layers  95   a ,  95   b . For example, if the first mask layers  95   a ,  95   b  are formed by using silicon oxide, the second mask layers  97   a ,  97   b  may be formed by growing a photosensitive resist to a film thickness of 1 μm. 
     Subsequently, as depicted in  FIG. 28 , dry etching is performed through the first mask layers  95   a ,  95   b  with the Deep RIE technique using the mixed gas (SF 6 +C 4 F 8 )  300  of SF 6  and C 4 F 8  while managing the processing time. As a result, the portions not covered with the first mask layers  95   a ,  95   b , i.e., the predetermined portions corresponding to the shape of the hairspring  108   d , are processed so that base materials  14   a  to  14   d  having a predetermined width and a predetermined height are formed. 
     Subsequently, as depicted in  FIG. 29 , the first mask layers  95   a ,  95   b  are patterned by using the second mask layers  97   a ,  97   b  as masks. The first mask layers  95   a ,  95   b  are made of silicon oxide (SiO 2 ) as described above and therefore, in this patterning, the masks may be removed by immersing the silicon substrate  61  having the second mask layers  97   a ,  97   b  formed thereon in a known etchant mainly composed of hydrofluoric acid. 
     As a result, as depicted in  FIG. 29 , the first mask layers  95   a ,  95   b  in the portions serving as the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   b  are removed, and the processed first mask layers  96   a ,  96   b  are formed, overlapping with the second mask layers  97   a ,  97   b  in a planar manner. On the flat surface  81  side, the mask on the portions serving as the groove portions  71   a  to  71   d  is opened so that the silicon base materials  14   a ,  14   b ,  14   c ,  14   d  are exposed. The first mask layer  95   b  on the flat surface  82  side is also removed in a predetermined portion corresponding to the shape of the hairspring  108   c . If the second mask layers  97   a ,  97   b  are photosensitive resists, the second mask layers  97   a ,  97   b  are not affected even when being immersed in the known etchant mainly composed of hydrofluoric acid. 
     Subsequently, as depicted in  FIG. 30 , dry etching is performed through the second mask layers  97   a ,  97   b  and the processed first mask layers  96   a ,  96   b  with the Deep RIE technique using the mixed gas (SF 6 +C 4 F 8 )  300  of SF 6  and C 4 F 8  while managing the processing time. As a result, the portions not covered with the second mask layers  97   a ,  97   b  and the processed first mask layers  96   a ,  96   b , i.e., the portions corresponding to the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   b , are subjected to etching processing so that the silicon substrate  62  is processed into the shape of the base materials  13   a  to  13   d  having a predetermined width and a predetermined height. 
     Subsequently, the second mask layers  97   a ,  97   b  and the processed first mask layers  96   a ,  96   b  are removed. As a result, the base materials  13   a  to  13   d  of the hairspring  108   d  as depicted in  FIG. 22  described above are formed. The groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   b  are respectively formed on the front surface (the flat surface  81 ) and the back surface (the flat surface  82 ) of the base materials  13   a  to  13   d.    
     The processed mask layers  96   a ,  96   b  may be removed, for example, by immersing the silicon substrate  62  in a known etchant mainly composed of hydrofluoric acid. The second mask layers  97   a ,  97   b  may be removed, for example, by immersing the silicon substrate  62  in a liquid of an organic solvent such as acetone. Subsequently, the hairspring  108   d  depicted in  FIGS. 14 and 15  can be formed in the same way as  FIGS. 23 to 26 . 
     As described above, the manufacturing method according to the fourth embodiment is a method of manufacturing the hairspring  108   d  provided with the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  that are stepped portions in the spring arms  203   a  to  203   d  and provided with the intermediate films  53   a  to  53   d  and the buffer films  23   a  to  23   d  in the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  as is the case in the third embodiment described above, and the groove portions serving as the stepped portions may be formed after the step of forming the outer shape. Although the manufacturing method of the fourth embodiment is described as the manufacturing method in which the intermediate films  53   a  to  53   d  and the buffer films  23   a  to  23   d  are formed in the groove portions  71   a  to  71   d  and the groove portions  72   a  to  72   d  having a concave shape, convex-shaped steps may also be manufactured by the same manufacturing method as is the case in the third embodiment. 
     Fifth Embodiment 
     An anchor  107  will be described as a drive mechanism of a timepiece incorporating a timepiece component of a fifth embodiment according to the present invention manufactured by a manufacturing method according to the fifth embodiment according to the present invention. In the fifth embodiment, portions identical to those of the first to fourth embodiments described above are denoted by the same reference characters used in the first to fourth embodiments and will not be described. 
       FIG. 31  is an explanatory view of the structure of the anchor  107  of the fifth embodiment.  FIG. 31  depicts a plane view of the anchor  107  of the fifth embodiment in a direction of the arrow X of  FIG. 1 .  FIG. 32  is an explanatory view of a cross-section taken along D-D′ in  FIG. 31 . In  FIGS. 31 and 32 , the anchor  107  implements a component of the balance (speed governing mechanism)  104  of the mechanical timepiece. 
     The anchor  107  regularly advances and stops the escape wheel  106  attempting to rotate according to the power transmitted through the train wheel  105 . The anchor  107  includes one beam portion  6  and two arm portions  7   a ,  7   b  extending in three respective different directions from a shaft hole  10  that is the rotation center of the anchor  107 . 
     A box portion  8  opened in a U shape is provided at a tip of the beam portion  6 . As an impulse pin performs a rotational reciprocating motion in a regular cycle according to the hairspring  108  ( 108   a  to  108   c ) and comes into contact with the box portion  8 , the anchor  107  reciprocates in a regular cycle around the shaft hole  10 . 
     Stone slots  9   a ,  9   b  are provided at tips of the arm portions  7   a ,  7   b . Components called pallet stones are pushed and fixed into the stone slots  9   a ,  9   b . The regular motion transmitted from the hairspring  108  ( 108   a  to  108   c ) through the impulse pin to the anchor  107  is transmitted to the escape wheel  106  by flicking the escape wheel  106  with the pallet stones so as to advance and stop the escape wheel  106 . 
     In the balance  104  as described above, the transmission efficiency of the power generated by the hairspring  108  ( 108   a  to  108   c ) may be increased by achieving the weight reduction of the components. Therefore, in the anchor  107  of the fifth embodiment, silicon having a light weight and a favorable processability is used as the first material forming the base material  15  of the anchor  107 . 
     As described above, since the anchor  107  of the fifth embodiment has the base material  15  formed by using silicon, the silicon forming the base material  15  may be processed by using the Deep RIE technique. For example, as depicted in  FIG. 31 , the anchor  107  in a hollow shape may be achieved easily by making a hole  12  in a portion of the anchor  107 . The hole  12  penetrates the anchor  107  in a thickness direction. By forming the anchor  107  in a hollow shape, the weight can further be reduced in addition to a weight reduction achieved by forming the base material  15  from silicon. 
     The anchor  107  of the fifth embodiment may be prevented from being damaged due to a strength reduction attributable to hollowing, by forming an intermediate film  53  on the surface of the base material  15  and further forming a buffer film  24  as an upper layer on the intermediate film  53 . In particular, by providing the intermediate film  53  formed by using the various materials described above on the surface of the base material  15 , the brittleness of silicon may be alleviated and, additionally, by providing on the surface of the intermediate film  53  the buffer film  24  formed by using the second material having a tenacity higher than that of silicon used as the first material, external impact to the anchor  107  may be mitigated to prevent a damage such as cracking and chipping due to stress concentration at corners, etc. 
     The box portion  8  is a portion coming into direct contact with the impulse pin and, if the buffer film  24  is provided on the surface of the box portion  8 , the transmission efficiency of the force from the impulse pin is reduced. Therefore, in the anchor  107 , as depicted in  FIG. 32 , the buffer film  24  is partially not provided on the same component, such as the box portion  8  of the anchor  107 , depending on purpose and function. 
     In the timepiece component such as the anchor  107 , the interlayer  53  of the box portion  8  may be removed in addition to the buffer film  24  of the box portion  8  depending on the specifications of the mechanical timepiece using the timepiece component, so as to expose the first material (in this example, silicon) that is the base material  15 . As a result, the force from the impulse pin may efficiently be transmitted to the escape wheel  106 . 
     In the fifth embodiment, the anchor  107  is formed into a hollow shape by providing the multiple holes  12  penetrating along the thickness direction; however, the shape of the anchor  107  is not limited thereto. For example, as described in the third embodiment, a groove portion serving as a stepped portion may be provided on the surface of the anchor  107 . As a result, the weight may be reduced further in addition to a weight reduction achieved by forming the base material  15  from silicon. 
     If the weight is reduced by providing the groove portion in this way, the buffer intermediate film  53  and the buffer film  24  may be provided along the shape of the groove portion or the groove portion may be filled with the buffer film  24 . As a result, damage may be prevented from occurring due to reduced strength attributable to hollowing. 
     In the fifth embodiment, the anchor  107  is taken as an example of a timepiece component reduced in weight by hollowing and prevented from being damaged due to a strength reduction attributable to hollowing in the description; however, this is not a limitation. Such a timepiece component may be achieved by other timepiece components such as gears (a wheel and pinion, an escape wheel) and a balance wheel, instead of, or in addition to, the anchor  107 . 
     Sixth Embodiment 
     A gear will be described as a drive mechanism of a timepiece incorporating a timepiece component of a sixth embodiment according to the present invention manufactured by a manufacturing method according to the sixth embodiment according to the present invention. In the sixth embodiment, portions identical to those of the first to fifth embodiments described above are denoted by the same reference characters used in the first to fifth embodiments and will not be described. 
       FIG. 33  is an explanatory view of the structure of the gear of the sixth embodiment. In  FIG. 33 , a gear  331  of the sixth embodiment includes a shaft hole  331   a  into which a shaft  332  is fitted. The gear  331  includes a base material  16  formed by using silicon. An intermediate film  54  is provided on a surface of the base material  16  located on an inner circumferential surface of the shaft hole  331   a . The intermediate film  54  may be formed by using the various materials described above. A buffer film  25  formed by using the second material is provided as an upper layer on the intermediate film  54 . 
     As described above, in the gear  331  of the sixth embodiment, by using silicon to form the base material  16 , the weight of the gear  331  is reduced and, by providing the intermediate film  54  and the buffer film  25  on the inner circumferential surface of the shaft hole  331 , external impact to the gear  331  may be mitigated to prevent a damage such as cracking and chipping due to stress concentration on corners etc. 
     Seventh Embodiment 
     An electret will be described as a timepiece component of a seventh embodiment according to the present invention manufactured by a manufacturing method according to the seventh embodiment according to the present invention. In the seventh embodiment, portions identical as those of the first to sixth embodiments described above are denoted by the same reference characters used in the first to sixth embodiments and will not be described. 
       FIGS. 34 and 35  are explanatory views of the electret of the seventh embodiment according to the present invention.  FIG. 34  depicts the electret viewed in an oblique direction, and  FIG. 35  depicts the electret viewed from the front. In  FIGS. 34 and 35 , an electret  340  is a charged object formed of a substance having dielectric polarization remaining (continuously forming an electric field) even when an electric field is eliminated in a dielectric substance dielectrically polarized by applying an electric field, and is used in a power generator, etc. not depicted. 
     The electret  340  includes a shaft hole  351  into which a shaft  341  is fitted. The electret  340  includes charged bodies  342  arranged radially from the shaft  341 , around the shaft  341 . Charged films are provided on front surfaces of the charged bodies  342 . The charged films are positively or negatively charged by being subjected to a treatment such as corona discharge. 
     Openings  343  are provided between the charged bodies  342  along the circumferential direction of a circle around the shaft  341 . As a result, the electret  340  may be reduced in weight. The charged bodies  342  are connected to the shaft  341  via an elastic member not depicted. The electret  340  is configured to perform an oscillating motion around the shaft  341  when vibration is externally applied. 
     The electret  340  of the sixth embodiment includes a base material formed by processing a silicon substrate by using the Deep RIE technique. The shape of the electret  340  is formed by the base material. The electret  340  has an intermediate film and a buffer film (both not depicted) provided at positions other than the portions provided with the charged films, i.e., other than the front surfaces of the charged bodies  342 . The intermediate film and the buffer film are provided in all the portions other than the portions provided with the charging films and are also provided on the inner circumferential surface of the shaft hole  351 . 
     The intermediate film is provided to cover the surface of the base material of the electret  340  other than the front surfaces of the charged bodies  342 . The buffer film is stacked as an upper layer on the intermediate film and is provided to cover the charged bodies  342  except the front surfaces. The intermediate film and the buffer film are respectively formed by using the same materials as those in the embodiments described above. 
     While a weight reduction is required, the electret  340  described above is an extremely fine component and therefore may cause a concern about reduced resistance to external impact when formed by using silicon, etc. Since the electret  340  of the sixth embodiment has the intermediate film and the buffer film provided at positions other than the front surfaces of the charged bodies  342  on the surface of the base material, a weight reduction may be achieved by forming the base material from silicon while the external impact may be mitigated by the intermediate film and the buffer film. 
     Additionally, the electret  340  has the intermediate film and the buffer film provided on the inner circumferential surface of the shaft hole  351  so that the inner circumferential surface of the shaft hole  351  and the outer circumferential surface of the shaft  341  come into contact with each other via the buffer film. As a result, even if an impact is applied to the electret  340  when the shaft  341  is fitted into the shaft hole  351 , the impact may be mitigated. Therefore, the electret  340  may be prevented from breaking or cracking when the shaft  341  is fitted into the shaft hole  351 . 
     Eighth Embodiment 
     A shaft stone will be described as a timepiece component of an eighth embodiment according to the present invention manufactured by a manufacturing method according to the eighth embodiment according to the present invention. In the eighth embodiment, portions identical to those of the first to seventh embodiments described above are denoted by the same reference characters used in the first to seventh embodiments and will not be described. 
       FIGS. 36 and 37  are explanatory views of a portion of the drive mechanism in the mechanical timepiece. In  FIG. 36 , the drive mechanism in the mechanical timepiece includes a shaft stone  361  that is a bearing formed of a stone such as ruby. The shaft stone  361  depicted in  FIG. 36  has a disk shape, and a shaft hole  361   a  is formed in a center portion. 
     In the mechanical timepiece, for example, as depicted in  FIG. 36 , a cutout  363  is formed in a bottom plate  362 , and the shaft stone  361  is held by fitting the shaft stone  361  into the cutout  363 . The cutout  363  includes projecting portions  362   a  projecting to come into contact with the shaft stone  361  at multiple positions and forms a shape different from the shape of the outer surface of the shaft stone  361 . 
     Rather than being in the same shape to which the shaft stone  361  is exactly fitted into the cutout  363 , the cutout  363  allows the multiple projecting portions  362   a  projecting toward the inside of the cutout  363  to come into contact with the outer circumferential surface of the shaft stone  361  so as to support the shaft stone  361 . The cutout  363  causes a contact force to act on the shaft stone  361  via the projecting portions  362   a  in directions indicated by arrows so as to support the shaft stone  361 . 
     When the shaft stone  361  is held by causing the projecting portions  362   a  to come into contact with the shaft stone  361 , the projecting portions  362   a  must be brought into strong contact with the shaft stone  361  for reliable holding; however, the strong contact places a burden on the shaft stone  361  at the positions of contact with the projecting portions  362   a . On the other hand, if the contact force of the projecting portions  362   a  against the shaft stone  361  is weak, it is difficult to sufficiently hold the shaft stone  361 . Particularly when the shaft stone  361  is arranged at the outer end portion (outer edge) of the bottom plate  362 , it is difficult to hold the shaft stone  361 . 
     In this regard, the shaft stone  361  of the eighth embodiment is formed by providing an intermediate film on a surface of a base material formed by using ruby, silicon, etc. as a first material and providing a buffer film as an upper layer on the intermediate film (detailed illustrations and reference characters of both films are not depicted). Thus, the base material of the shaft stone  361  is covered with the interlayer film and the buffer film. 
     By achieving the shaft stone  361  having the intermediate film and the buffer film provided on the surface of the base material in this way, the shaft stone  361  may be held reliably without damaging the shaft stone  361  even when the projecting portions  362   a  are brought into strong contact with the shaft stone  361  so as to strongly hold the shaft stone  361 . 
     The shaft stone  361  is not limited to the shape depicted in  FIG. 36 . For example, the shaft stone  361  having the shape depicted in  FIG. 36  may be replaced with a shaft stone  371  having a shape as depicted in  FIG. 37 . The shaft stone  371  is supported by being fitted into a cutout  373  cut inward from the end portion (outer edge) of the bottom plate  362  and widened laterally inside the bottom plate  362 . The shaft stone  371  has the same shape as the cutout  373  and forms a substantially T shape widened laterally on the inner side of the end portion of the bottom plate  362 . The shaft stone  371  has a shaft hole  371   a  formed at a position shifted from the center portion toward an end. By using the shaft stone  371  acquired by processing a silicon material with photolithography, such a different shape is easily fabricated. 
     By using the shaft stone  371  and the cutout  373  having such a shape, the shaft stone  371  may be held stably. As a result, the shaft hole  371   a  may be arranged at a position close to the end portion (outer edge) of the bottom plate  362 . The shape of the shaft stone is not limited to the shapes depicted in  FIGS. 36 and 37  and, for example, a triangular shaft stone may be supported by the bottom plate  362  such that a vertex is arranged at the end portion (outer edge) of the bottom plate  362 . Such a triangular shaft stone may have a shaft hole provided in the vertex arranged at the end portion (outer edge) of the bottom plate  362 . 
     Ninth Embodiment 
     A backlash compensating member will be described as a timepiece component of a ninth embodiment according to the present invention manufactured by a manufacturing method according to the ninth embodiment according to the present invention. The backlash compensating member is provided in a mechanism mutually engaged with a gear (or screw) to transmit a motion such as the train wheel  105  and a screw in the mechanical timepiece so as to compensate a gap (so-called backlash) intentionally provided in the direction of motion of the gear (or screw) in the mechanism. The backlash compensating member is described as a conventional technique in Japanese Patent No. 4851945, for example. 
     The backlash compensating member is provided, for example, at a position of a tooth (or screw thread) at which a gear (or screw) is engaged with an engagement counterpart. Alternatively, the backlash compensating member is provided between the gear (or screw) and the engagement counterpart. The backlash compensating member includes a tooth portion engaged with the gear (or screw), and rotates in conjunction with the gear (or screw) when the rotation of the gear (or screw) is transmitted through the tooth portion. The tooth portion is configured to elastically deform with respect to the rotation direction. This allows the backlash compensating member to compensate a backlash between the gear (or screw) and the engagement counterpart. 
     In this backlash compensating member, at least the tooth portion is made up of a base material, and the intermediate and buffer films described above are provided on the tooth portion made up of the base material. As a result, an impact caused by transmission of power of the gear (or screw), etc. may be mitigated so as to prevent cracking or chipping of the backlash compensating member attributable to a stress concentrating at the tooth portion due to a collision of the gear (or screw) against the tooth portion of the backlash compensating member. Additionally, by providing the buffer film, the impact may be mitigated, so that the backlash compensating member and the gear or the screw, etc. colliding with the backlash compensating member may be prevented from being damaged. 
     INDUSTRIAL APPLICABILITY 
     As described above, the timepiece component and the method of manufacturing a timepiece component according to the present invention are useful for a timepiece component constituting a mechanical component in a timepiece and a method of manufacturing the timepiece component and is particularly suitable for a timepiece component used in a speed governing mechanism of a mechanical timepiece and a method of manufacturing the timepiece component. 
     EXPLANATIONS OF LETTERS OR NUMERALS 
     
         
         
           
               108 ,  108   a ,  108   b ,  108   c  hairspring 
               2  spring unit 
               3  collet 
               4  stud 
               107  anchor 
               6  beam portion 
               7   a ,  7   b  arm portion 
               8  box portion 
               9   a ,  9   b  stone slot 
               10  shaft hole 
               11   a - 11   d ,  13   a - 13   d  base material 
               21   a - 21   d ,  22   a - 22   d ,  23   a - 23   d ,  24   a - 24   d ,  25   a - 25   d  buffer film 
               31  through-hole 
               32  connection portion 
               51   a - 51   d ,  52   a - 52   d ,  53   a - 53   d ,  54 ,  55   a - 55   d  intermediate film 
               60 ,  61 ,  62  silicon substrate 
               80  side surface 
               81 ,  82  flat surface 
               331  gear 
               331   a  shaft hole 
               340  electret 
               341  shaft 
               342  charged body 
               351 ,  361   a ,  371   a  shaft hole 
               361 ,  371  shaft stone 
               362  bottom plate 
               363 ,  373  cutout 
               500 ,  510 ,  520 ,  530  exposure mask