Abstract:
A microactuator design and fabrication method for an improved magnetic microactuator incorporating mechanical stroke limiters and integrated connections between the flex on suspension and slider. The stroke limiters, also referred to as bumper system, and integrated connections enable low power, mechanically robust operation of the microactuator during high seek operations. In addition, improved head gimbal assembly yield results due to the integrated head connections formed on the microactuator.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     None. 
     BACKGROUND OF THE INVENTION 
     The present invention is related to an improved magnetic microactuator for disc drives having integrated head connections and limiters. 
     Disc drive systems are well-known in the art and comprise several discs, each disc having concentric data tracks for storing data. The discs are mounted on a spindle motor, which causes the discs to spin. As the discs are spinning, a slider suspended from an actuator arm “flies” a small distance above the disc surface. The slider carries a transducing head for reading from or writing to a data track on the disc. 
     In addition to the actuator arm, the slide suspension comprises a bearing about which the actuator arm pivots. A large scale actuator motor, such as a voice coil motor (VCM) is used to move the actuator arm over the surface of the disc. When actuated by the VCM, the slider can be moved from an inner diameter to an outer diameter of the disc along an arch until the slider is positioned above a desired data track on the disc. Called tracking, this method of positioning the slider above the desired track on the disc allows the transducing head on the slider to either read from or write data to a selected track on the disc. 
     The areal recording density of the disc is typically given in tracks per inch (TPI), which is an indication of the number of tracks per inch along the radius of the disc. There is constant pressure to increase the areal density of discs, and thus increase the number of tracks per inch on the disc. As the tracks per inch increase, the accuracy of the system used to position the transducing head above the desired track on the disc must increase in proportion. In an attempt to improve the tracking ability of the slider, secondary microactuators have been placed between the suspension and the slider. 
     One such microactuator comprises a stationary portion, or stator, as well as a movable portion, or rotor. The rotor is connected to the stator by compliant springs, which allow the rotor to be movable relative to the stator. To move the rotor, the microactuator comprises a motor system, such as a magnetic circuit having either a moving coil or moving magnet portion. 
     These current microactuator designs are limited in seek performance because the mass-spring resonant mode of the silicon springs connecting the stator and rotor is excited by the primary VCM during seeking. More specifically, as seek accelerations increase beyond 100 G&#39;s, the microactuator motor cannot create enough force to control the rotor position during seek operations. Further, high seek accelerations induce large amplitude ringing of the rotor at the mass spring mode (typically 1,000-3,000 Hz), which unacceptably increases the required settling time. In extreme cases, the rotor may contact the stator at significant velocity. This contact may cause silicon chipping, which creates particles that may cause a catastrophic failure in a disc drive. The contact may also cause silicon cracking, which may eventually lead to the failure of the microactuator device. 
     In addition to problems associated with increased seek acceleration, there remain challenges to manufacturing microactuators. Currently, the slider is attached to the microactuator using a flex on suspension (FOS) or flex circuit. When connecting the flex circuit to the slider, the relatively large size of the flex circuit results in a fairly coarsely positioned slider. In addition, these mechanical connections have an effect on the stiffness of the microactuator. As a result, it is possible the slider will be positioned on the microactuator having a mechanical bias of as many as 10 microns or more. Previously, this mechanical bias caused by the connection of the head to the flex on suspension was not a problem because the stroke size of the rotor relative to the stator was large enough to accommodate some mechanical bias. Further, the control system of the microactuator could be used to compensate for any such mechanical bias. However, as seek accelerations increase and settling times decrease, it is desirable to limit the stroke size of the microactuator. As a result, any manufacturing processing which results in a mechanical bias when attaching the slider to the microactuator becomes unacceptable. 
     Thus, there is a need in the art for a microactuator having a decreased stroke size, increased robustness during use at high seek accelerations, and resistance to breakage caused by physical contact between the rotor and stator. Furthermore, there is a need in the art for such a microactuator which is easy to manufacture using existing manufacturing methods. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is a microactuator design and fabrication method for an improved magnetic microactuator that incorporates mechanical stroke limiters and integrated connections between the flex on suspension and slider bond pads. The stroke limiters (also referred to as seek bumpers) and integrated connections enable low power, mechanically robust operation of the microactuator during high acceleration seek operations. In addition, the present invention allows improved head gimbal assembly (HGA) yield due to the integrated head connections formed on the microactuator. Furthermore, the embodiment allows for integrated piezoresistive position sensors. 
     The microactuator comprises a stator, a rotor carrying a slider, the rotor being movable with respect to the stator, and a seek bumper system comprising a pliable material located on the stator and the rotor at a location where the rotor contacts the stator during seek operations. The seek bumpers limit silicon-on-silicon contact and reduce the risk of chipping or cracking. In addition to the seek bumpers, the gap between the rotor and stator is made smaller. With a smaller gap, the rotor deflection due to the VCM seek acceleration can be reduced so that the deflection times the spring constant is less than the force available from the microactuator. 
     To allow for a smaller gap, and to remove mechanical biases, the microactuator is formed having integrated head connections by using buried and surface wires formed on the rotor and the stator. In this way, the connections from the rotor to the head can be made directly, while the connections from the microactuator to the flex circuit can be made at the stator. This allows the desired gap width between the stator and rotor to be sufficiently small, while also removing any flex bias which would result in inadequate space between the rotor and the stator. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a disc drive actuation system for positioning a slider over tracks of a disc. 
     FIG. 2 is a perspective view of a microactuator according to the present invention. 
     FIG. 3 is a top perspective view of a portion of the microactuator showing the stator and the rotor. 
     FIGS. 4A-4C are perspective views of a portion of the microactuator showing in detail the bumper pads. 
     FIG. 5 is a bottom perspective view showing the slider pedestal and head connectors, as well as the piezoresistive sensor. 
     FIG. 6 is a perspective view of a portion of the microactuator showing in detail the bond pads between the slider and the microactuator. 
     FIG. 7A is a bottom perspective view of the microactuator showing a flat pedestal. 
     FIG. 7B is a perspective view showing a method of attaching a slider to the microactuator having a flat pedestal. 
     FIG. 8 is a top perspective view of a portion of the microactuator showing lines A-A′ and B-B′. 
     FIGS. 9-22 illustrate the manufacturing process flow for forming the microactuator feature illustrated by line A-A′. 
     FIGS. 23-36 illustrate the manufacturing process flow for forming the microactuator feature illustrated by line B-B′. 
     FIGS. 37-41 illustrate the manufacturing process flow for forming the microactuator feature illustrating the process for manufacturing a microactuator having a flat pedestal taken along cut line B-B′. 
     FIGS. 42A and 42B are top perspective views showing an alternate bumper system formed of epoxy. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 is a perspective view of a disc drive actuation system  10  for positioning a slider  12  over a selected data track  14  of a magnetic storage medium  16 , such as a disc. The actuation system  10  includes a voice coil motor (VCM)  18  arranged to rotate a slider suspension  20  about an axis  22 . The slider suspension  20  includes a load beam  24  connected to an actuator arm  26  at a slider mounting block. A flexure  28  is connected to the end of the load beam  24 , and carries the slider  12 . The slider  12  carries a magneto-resistive (MR) element (not shown) for reading data and a coil element for writing data on the concentric tracks  14  of the disc  16 . The disc  16  rotates around an axis  30 , which causes the slider  12  to “fly” a small distance above the surface of the disc  16 . 
     FIG. 2 is a perspective view of a microactuator  40 . The microactuator  40  comprises a microactuator body  42  and a magnet containing portion  44 . The microactuator body  42  comprises a stator  46  and a rotor  48 . The stator  46  is connected to the rotor  48  by a plurality of compliant springs  50 . The compliant springs  50  illustrated in FIG. 2 are for illustrative purposes only and the actual number and design of compliant springs  50  may vary. Also shown is the slider  12 , slider bond pads  52 , and ball bonds  54 . Located on a surface of the rotor  48  is a coil  56 , slider vias  58 , and via wires  60 . Located on the stator  46  are bond pads  62  and bond pad wires  64 . Slider bumpers  66  are located on the slider body  42  between the stator  46  and the rotor  48 . 
     The slider  12  is connected to the microactuator body  42  using the ball bonds  54 . The microactuator  40  functions by providing a current to the coil  56  on the rotor  48 . The current through the coil  56 , when combined with a magnet carried by the magnet containing portion  44 , creates a vertical magnetic circuit which actuates the rotor portion  48  of the microactuator  40 . The compliant springs  50  allow the rotor  48  to move relative to the stator  46 . Thus, the slider  12  attached to the rotor  48  can be microactuated. 
     Slider vias  58  on the rotor  48  form an electrical connection from the top side of the microactuator body  42  to the bottom side (as viewed in FIG.  2 ). The slider  12  connects to the bottom of the microactuator body  42  so that an electrical connection is made from the slider  12  to the vias  58  on the microactuator at the ball bonds  54 . In this way, a read or write signal sensed by the slider  12  is transmitted from the slider  12  to the microactuator  40  using vias  58  on the rotor  48 . Wires  60  on the top of the microactuator body  42  extend from the vias  56  on the rotor  48  across the compliant springs  50  to the bond pads  62  on the stator  46 . From the bond pads  62  on the stator  46 , a connection can be made to a flex circuit (not shown) or other remote circuitry. 
     FIG. 3 is a top perspective view of a portion of the microactuator  40  with the magnet portion  44  removed to more clearly illustrate the present invention. Visible is the rotor  48 , stator  46 , coil  56 , head vias  58 , via wires  60 , stator bond pads  62 , and stator wires  64 . Also shown are seek bumpers  66  between the rotor  48  and stator  46 . Further, a piezoresistive sensor  70  is located at the rear of the microactuator  40  and the coil  56  is provided with the coil jumper  72 , which allows current to flow through the coil  56 . 
     Compliant lateral springs and large rotor mass create the requirement to apply large forces to maintain positional control during large-acceleration seeks. As a result, the microactuator motor cannot create enough force to control the rotor position as seek accelerations increase beyond 100 G&#39;s. These high seek accelerations induce large amplitude ringing of the rotor at the mass-spring mode, typically 1,000-3,000 Hz, which unacceptably increases settling time. In extreme cases, the rotor may contact the stator at significant velocity, causing silicon chipping or silicon cracking, either of which are highly undesirable. 
     One solution is to place the seek bumpers  66  on the inside edge of either the rotor  48  or stator  46  or both such that when in contact, the contact occurs at the bumpers  66 . This prevents silicon on silicon contact, and reduces the risk of chipping or cracking. In addition to the mechanical benefits of seek bumpers  66 , the gap between the rotor  48  and stator  46  is made smaller. With a smaller gap, the rotor  48  deflection due to VCM seek acceleration is reduced. This makes it possible to ensure the microactuator has available force that is greater than the deflection times the spring constant of the beams  50  of the microactuator  40 . Eliminating the settling time increase by ensuring the microactuator  40  is able to control its own position immediately after the end of the VCM seek greatly improves the functionality of the microactuator  40 . 
     In order to reduce the gap width between the rotor  48  and stator  46 , the recording head electrical connection method must be changed. Currently, the FOS circuit is independent of the microactuator body  40  for the recording head leads, so that when assembled it is possible that the FOS may bias the rotor  48  several microns in either direction. If the desired gap width between the rotor  48  and stator  46  is sufficiently small such that the flex bias created by the FOS moves the recording head to where there is not adequate space between its edge and the bumper  66 , the electrical connections must be routed to remove the flex bias. One method to eliminate the flex bias is to integrate the electrical leads into the silicon body of the microactuator  40  and route them from the rotor  48  to the stator  46  where they can then be connected to the flex circuit without creating any mechanical bias of the rotor  48 . 
     FIG. 3 illustrates one embodiment of routing the necessary electrical connects to the stator  46 . To do so, the connections make use of both surface beam wires and embedded beam wires, as well as through-wafer vias. More specifically, in one embodiment illustrated in FIG. 3, the bond pads  62  on the lower portion of the stator  46  (as viewed in FIG. 3) comprise a first write bond pad  80 , a first read bond pad  82 , coil bond pad  84 , a piezoresistive sensor voltage source bond pad  86 , and a piezoresistive sensor voltage sense bond pad  88 . Located on the upper portion of the stator  46  (as viewed in FIG. 3) is a second write bond pad  90 , and second read bond pad  92 , a piezoresistive sensor voltage ground bond pad  94 , a slider ground bond pad  96 , and a second coil bond pad  98 . 
     On the rotor  48 , the head vias  58  comprise a first write via  100 , and first read via  102 , a slider ground via  104 , a second read via  106 , and a second write via  108 . The first and second write head vias  100 ,  108  are connected to the write bond pads  80 ,  90  on the stator  46  by buried wires  110  and  112 . The first and second read via  102 ,  106  are connected to the first and second read bond pads  82 ,  92  on the stator  46  using surface wires  114  and  116 . The slider ground via  104  is connected to the slider ground bond pad  96  using a surface wire  118 . 
     To monitor the relative position of the rotor  48  with respect to the stator  46 , it is common to use some form of sensor, such as a piezoresistive sensor  70  integrated into the spring flexure. When such a sensor is used, the connections to the piezoresistive sensor are likewise formed using surface and embedded wires on the stator  46 . 
     The piezoresistive sensor  70  comprises a voltage ground via  120 , a voltage source via  121 , and a voltage sense via  122 . The piezoresistive sensor voltage source bond pad  86  is connected to the voltage source via  121  using a buried wire  124 . The piezoresistive sensor voltage sense bond pad  88  is connected to the voltage sense via  122  using a second embedded wire  125 . The ground bond pad  94  is connected to the voltage ground via  120  using a third buried wire  126 . 
     To actuate the microactuator, current must be provided to the coil  56 . The necessary connections to the coil  56  are also made using buried wires. Specifically, the first coil bond pad  84  is connected to the coil  54  using an embedded beam wire  128 . The second coil bond pad  98  is also connected to the coil  54  using an embedded wire  130 . 
     FIG. 3 illustrates one method of integrating the necessary connections into the microactuator body  42 . However, the invention is not limited to any one configuration of surface or embedded wires, their location, or the location of the vias and bond pads. However, it may be preferable to use embedded wire for those applications which require a larger current through the wire. Embedded wires have a larger cross-sectional area, making it possible for the embedded wires to carry larger amounts of current. Thus, the writer portion of the magnetic transducing head, which receives a larger amount of current than the reader portion, is connected on the microactuator  40  using embedded wires  110 ,  112 . Similarly, the connections to the reader portion of the magnetic transducing head may be formed of surface wires  114 ,  116 , because the reader does not require a large current flow. However, it is possible to use either embedded or surface wires as desired or required to allow for all the necessary connections between the head and the flex circuit. 
     FIG. 4A is a perspective view of a detail of the microactuator more clearly illustrating the seek bumpers  66 . FIG. 4A illustrates a portion of the rotor  48  and a portion of the stator  46 , as well as a portion of the beams  50  which movably connect the rotor  48  to the stator  46 . Located between the rotor  48  and stator  46  is the seek bumper  66 , comprising first and second bumper pads  140 ,  142 . The first bumper pad  140  is located on the rotor  48 , while the second bumper pad  142  is located on the stator  46 . 
     The bumper pads  140 ,  142  may be formed of any suitable material which is capable of absorbing the stress caused when the rotor  48  contacts the stator  46 . Specifically, the bumper pads  140 ,  142  may be formed of a metal or epoxy material. Furthermore, the location of the bumper pads  140 ,  142  may be any suitable location between the rotor  48  and the stator  46  such that any chipping or cracking caused by contact between the rotor  48  and stator  46  is reduced or eliminated. Most preferably, the bumper pads  140 ,  142  are positioned near a top surface of the microactuator  40 . In addition, the bumpers may be recessed from the top or bottom surface of the microactuator. 
     It is preferred to form the bumper pads  140 ,  142  so that the pads  140 ,  142  are large enough to extend away from the rotor  48  and the stator  46  so that any contact between the rotor  48  and stator  46  occurs at the bumper pads  140 ,  142 , rather than the silicon of the rotor  48  and stator  46 . As such, the bumper pads  140 ,  142  may be of any desired shape or size to achieve this function. 
     Though a typical gap spacing between the rotor  48  and stator  46  results in a plus or minus 50 micron stroke range, it is desired to reduce this stroke range according to the present invention. Thus, the space between the rotor bumper pad  140  and stator bumper pad  142  is made with a desired gap spacing of approximately -15 microns. However, the invention is not so limited, and any gap spacing which allows the microactuator to function according to the present invention is suitable. 
     In addition to forming the bumper pads  140 ,  142  of a metal or an epoxy, it may be possible to form the bumpers  66  of a material which utilizes electrostatic attractive forces to prevent repetitive physical contact between the bumpers  66  during seeks by electrostatically clamping the metal bumpers  66  until the seek is completed. In such an instance, electrical connections to the metal bumpers  66  would need to be added. 
     Further, as shown in FIG. 4B, a fluid air bearing  144  between the rotor and stator bumpers  66  could be used to prevent or mitigate contact between the rotor  48  and the stator  46 , such as using squeeze film dampers. Further yet, as shown in FIG. 4C, repulsive magnet “virtual bumpers”  146 ,  148  that use repulsive magnetic forces to minimize or even eliminate the mechanical contact between the rotor  48  and stator  46  may be possible. Finally, though shown in FIGS. 4A-4C with bumper pads  140 ,  142  located on both the stator  46  and the rotor  48 , the invention is not so limited. The bumper  66  may be formed on the rotor  48 , the stator  46 , or both. 
     FIG. 5 is a bottom perspective view of the microactuator  40 . Shown in the bottom view of FIG. 5 is the rotor  48  and stator  46 . Once again, the flexible beams  50  which connect the stator  46  to the rotor  48  are also visible. A gap  150  separates the rotor  48  from the stator  46  allowing the rotor  48  to move relative to the stator. The rotor  48  also comprises a slider pedestal  152  surrounded by a trench  154 . At the top edge of the slider pedestal  152  are the integrated head connections  156  which provide an electrical connection to the top of the microactuator body  42  at the vias  58  (shown in FIGS.  2  and  3 ). Also located on the slider pedestal  152  is a raised portion  158  which may further serve to align a slider on the slider pedestal  152 , and ease connections from the integrated head connections  156  to the slider head connections. 
     More clearly visible in FIG. 5 is the piezoresistive sensor  70 . The piezoresistive sensor  70  comprises piezoresistors  160  located on a beam spring  50 . The piezoresistors  160  are connected to the vias  120 ,  121 ,  122 , which provide a connection from the bottom side of the microactuator  40  visible in FIG. 5 to the top side shown in FIG.  3 . Piezoresistive position sensors are known in the art, and typically comprise a resistor bridge wherein two resistors  160  are placed on each side of the beam  50 . The differential change in resistance as the beam  50  bends can be measured to determine the deflection of the beam  50 . 
     One reason for locating the piezoresistive sensor  70  on a bottom side of the microactuator  40  is to provide enough space for the piezoresistive resistor  160  located on the beam spring  50 . However, the invention is not so limited, and if there is available space on the top surface of the microactuator (FIG. 3) which is not required for any embedded or surface wires, it is possible to form the piezoresistive sensor  70  on a top surface of the microactuator  40 . 
     FIG. 6 is a side perspective view showing a portion of the slider pedestal  152  and a slider  12 . Also visible in FIG. 6 is a ball bond source  170 . As shown in FIG. 6, the integrated head connections  156  in the form of vias  58  are formed at the raised portion  158  of the slider pedestal  152 . As such, the raised integrated head connections  156  provide a location for attaching the slider  12  to the slider pedestal  152 . More specifically, the slider  12  can be placed on the slider pedestal so that the ball bond locations  170  are easily matched to the integrated head connectors  156  at the raised portion  158 . This arrangement eases the manufacturing process by providing the surface metal conducts to the slider pedestal level. 
     FIGS. 7A and 7B illustrate an alternate method of attaching a slider  12  to a microactuator  40 . Shown in FIG. 7A is a portion of an alternate microactuator  180  with the stator  46 , rotor  48 , flexible beam springs  50  connecting the two, and a slider pedestal  182 . The slider pedestal  182  comprises five integrated head connections  184 . In contrast to the previously described slider pedestal, the slider pedestal  182  in FIG. 7A is flat and does not contain a raised portion  158 . 
     FIG. 7B shows an alternate method of attaching a slider  12  to a slider pedestal  182  having no raised portion. In FIG. 7B, the slider  12  bond pads  52  are aligned with the integrated head connections  184  on the slider pedestal  182 . Once so positioned, the slider  12  can be attached to the slider pedestal  182  using any suitable method, such as welding or bonding. As shown in FIG. 7B, a plurality of ball bond sources  186  are provided to form the connection between bond pads  52  on the slider  12  and the integrated head connections  184  of the slider pedestal  182 . As described more fully below, there are advantages and disadvantages to the two slider pedestal designs shown in FIG.  6  and FIG. 7A,  7 B, most of which relate to manufacturing processes. 
     The method of forming a microactuator according to the present invention is described with reference to FIGS. 9-41 below. One of the main advantages of the present invention is that all features may be formed using conventional manufacturing methods. 
     To illustrate, two cut lines are present on FIG.  8 . The cut line A-A′ illustrates how the features near the coil containing end of the microactuator are formed, while cut line B-B′ illustrates how the features near the slider holding end of the microactuator are formed. FIGS. 9-22 illustrate a cross-sectional view taken along cut line A-A′ shown in FIG. 3, while FIGS. 23-36 illustrate a cross-sectional view taken along cut line B-B′. The manufacturing process is broken down into fourteen steps. FIGS. 9-22 illustrate fourteen steps of forming the features along A-A′; while FIGS. 23-36 illustrate fourteen steps of forming the features along B-B′. 
     The process of forming that portion of the microactuator illustrated by A-A′ is described first with respect to FIGS. 9-22. Shown in FIG. 9 is a silicon wafer indicated by  190 , a layer of photoresist  192 , and two piezoresistors  194 . Hereinafter, side  1  of the wafer  190  refers to the top side of the wafer, as viewed in FIGS. 9-36, while side  2  of the wafer  190  refers to the bottom. The microactuator is generally formed at the wafer level, using any suitable material, such as silicon. As illustrated in FIG. 9, a first step in forming the microactuator is to form the piezoresistors  194  in the silicon. The piezoresistors  194  are defined using an oxide or photoresist mask  192 . The piezoresistors  194  may be formed of any suitable method, such as ion implantation to dope the silicon to create the resistors  194 . After doping, the wafer  190  is annealed to diffuse the dopants. 
     FIG. 10 illustrates the next step in forming the microactuator. As shown in FIG. 10, certain features of the microactuator are formed by etching. Specifically, vias  196  are formed through the wafer  190  to allow for a connection between a top and a bottom surface of the microactuator. In addition, the embedded wires  198 , including wires  200  for forming the coil  200  are etched. Next, as shown in FIG. 11, the trenches forming the vias  196  and wires  198 ,  200  are insulated using any suitable material, such as by applying a layer of silicon nitride  202 . After depositing the insulator  202 , the trenches  196 ,  198 ,  200 , are back filled with a metal  204 , as shown in FIG.  12 . The metal  204  may be any suitable metal for forming the embedded wires, vias, and coil; a particularly suitable metal is copper. In the step illustrated by FIG. 13, a chemical mechanical polish (CMP) is performed on both side  1  and side  2  of the wafer  190  to planarize both surfaces. 
     In the next step, illustrated in FIG. 14, an insulating nitride  206  is. deposited on side  1  of the wafer  190 . The insulating nitride  206  may be deposited using any suitable method, such as PECVD (plasma enhanced chemical vapor deposition). During the next step illustrated in FIG. 15, no feature is formed on the wafer  190  along A-A′. However, as described below with reference to FIG. 28, the slider pedestal is etched on side  2  of the wafer. Due to the cut line A-A′, the pedestal recession is not shown in the cross-sectional view of FIG.  15 . 
     FIG. 16 illustrates the next step in forming the microactuator. Shown in FIG. 16, an insulator  208  is deposited on side  2  of the wafer  190 . The insulator  208  may be deposited using any suitable method, such as PECVD. Next, as illustrated in FIG. 17, an etch is performed at the vias  196 , some embedded wires  198 , and the coil  200 . This etch extends through the nitride  206  to the silicon and copper trenches  204 , and is performed on side  1  and side  2 . The etches are indicated at  210  and provide a location for forming connections to the embedded wires  198  and coil  200 . In FIG. 18, a surface metal  212  is deposited and patterned on side  1  and side  2  of the wafer. The surface metal  212  forms connections at the wires  198  and the jumper  72  on the coil  200 . The surface metal  212  may be any suitable metal, such as tantalum and/or gold. 
     During the step illustrated in FIG. 19, once again, no feature is formed on the wafer  190  along cut line A-A′. However, as described below with reference to FIG. 32, the seek bumper etch is performed during this step. 
     FIG. 20 illustrates the step of etching a tub  214  and the beams  216 . In performing this etch, a mask  218  is deposited, the mask is patterned, and a DRIE (deep reactive ion etch) is performed from side  2  of the wafer  190 . FIG. 21 illustrates the next step in forming the microactuator. In FIG. 21, the side  2  etch mask  218  has been stripped. An oxide layer  220  is deposited on side  2 , including in the beams  216 . The oxide in the beams  216  serves as an etch stop during the following PECVD etch. Also during this step, a mask  222  is applied on side  1  of the wafer  190 . The mask  222  is patterned, and an etch is performed in the silicon of side  1 . Thus, in step  2 , the beams  216  are completed by etching from side  1  of the wafer  190  until the etch stop  220  is reached that has been deposited in side  2 . This ensures the etch for the beams  216  results in a high aspect ratio etch. 
     In a last step, illustrated in FIG. 22, the resist mask  222  is stripped, and the oxide etch stop  222  is etched and released from side  2  of the wafer  190 . Thus, FIGS. 9-22 illustrate a standard process method for creating all the features of the microactuator taken along cut line A-A′. 
     At the same time the process flow illustrated in FIGS. 9-22 are occurring, FIGS. 23-36 illustrate the processes which also occur along cut line B-B′ of FIG.  8 . FIG. 23 illustrates the first step in forming the microactuator. Shown in FIG. 23 is the wafer  190  and layer of photoresist  192 . During this step, the piezoresistive sensors are formed, as illustrated in FIG.  9 . However, no features are formed along cut line B-B′. 
     FIG. 24 illustrates the next step in the process taken along B-B′. In FIG. 24, an etch is performed to create embedded wires  198 , several through-wafer vias  196 , and the beginning of bumper trenches  224 . FIG. 25 illustrates the next step of insulating the trenches  198 , vias  196 , and bumper trench  224  with a layer of silicon nitride  202 . In FIG. 26, the trenches and vias are back filled with a metal  204 , such as copper. In FIG. 27, the copper  204  is polished off both side  1  and side  2  of the wafer  190 , using any suitable process, such as a chemical mechanical polish. Next, as illustrated in FIG. 28, the insulating nitride  206  is deposited on side  1  of the wafer  190 . The nitride is deposited using PECVD. 
     In FIG. 29, an etch is performed on side  2  to create the pedestal recession  226 . In FIG. 30, the insulator  208  is deposited on side  2  of the wafer using PECVD. FIG. 31 shows the next step of etching electrical connections to bond pads through the nitride to the silicon and copper trenches. This etch is performed on both side  1  and side  2  of the wafer  190 . These etches are indicated at  210 . 
     FIG. 32 illustrates the step of depositing and patterning the surface metal  212  to form the bond pads and other metalized features on side  1  and side  2  of the wafer  190 . FIG. 33 illustrates the step of applying a photoresist pattern  228  on side  2  of the wafer  190 . Side  2  is patterned and a deep reactive ion silicon etch is performed from side  2  to form an underside  230  of the seek bumper. As shown in FIG. 34, side  2  is stripped of the etch mask. A second layer of photoresist  232  is applied and a second pattern is developed. As a result of this pattern, a DRIE silicon etch is performed on side  2 . During this etch, a first portion of the flexible beams is etched, the slider trench  236  is formed, and an etch is performed to form the flexible beam  238  leaving side bumpers  240 . As illustrated in FIG. 35, side  2  is stripped of the photoresist mask. Next, a layer of oxide etch stop  242  is deposited and an etch is performed on side  1  of the wafer  190 . During this etch, the remainder of the flexible beams  234  is etched from side  1  to the oxide etch stop of side  2 . 
     Finally, in the step illustrated in FIG. 36, the photoresist mask is stripped from side  1  and the oxide etch stop  242  is etched from side  2 . At this point, the wafer is released. Thus, all the features of the microactuator can be made using standard manufacturing processes. The above discussion is merely a summary of this manufacturing process, and those skilled in the art will recognize that fewer or greater steps may be required to form these structures as desired. Similarly, though shown as having a side  1  and a side  2 , many of the manufacturing processes involve flipping the wafer over to perform processes on either side. However, FIGS. 9-36 do not indicate this flipping of the wafer, but rather indicate generally the procedures formed on side  1  and side  2  of the wafer. 
     FIGS. 37-41 illustrate an alternate method of forming the vias through the microactuator. FIGS. 37-41 illustrate a method of forming a microactuator illustrated in FIG. 7A-7B. Specifically, FIGS. 37-41 illustrate forming a microactuator wherein the slider pedestal  48  does not contain a raised portion, but rather is flat. Such a design may have manufacturing advantages, particularly because it is not necessary to apply a pattern over the raised portion of the slider pedestal. 
     FIG. 37 is a cross-sectional view of a microactuator taken along cut line B-B′. The microactuator comprises a wafer  250 . Just as in the previous example, the first step, as illustrated in FIG. 37 is to apply a layer of photoresist  252  to implant the piezoresistive sensors into the silicon. The piezoresistive sensors are not shown in the cross-sectional view taken along cut line B-B′, as such FIG. 37 merely illustrates a cross-section of the wafer  250  and the photoresist mask  252 . 
     In a next step illustrated by FIG. 38, the embedded wires  254 , bumper trenches  256 , and through-wafer vias  258  are etched into side  1  of the wafer  250 . The slider pedestal recession region  260  is etched into side  2  of the wafer  250 . 
     Next, as illustrated in FIG. 39, the trenches are insulated with a layer of silicon nitride  262 . The trenches are back filled with copper  264 , as illustrated in FIG.  40 . Then, as illustrated in FIG. 41, a chemical mechanical polish is performed on side  1  to remove the excess copper. On side  2 , a chemical mechanical polish, or a wet etch, is performed on the copper of side  2 , making sure to leave a bonding surface  266  to accommodate the head bond pads of the slider. In addition to forming the bond pads  266  using some form of etch, additional metal may be deposited on the bonding surface prior to the etch and pattern. 
     The remaining steps for cross-section B-B′ are similar to the standard fabrication method described with reference to FIGS. 23-36 above. As such, the alternative method of forming the microactuator as illustrated in FIGS. 37-41 may be preferred because it simplifies patterning of head bond pads on side  2 . 
     FIGS. 42A and 42B are bottom perspective views of a detail of the microactuator illustrating alternatives for forming the bumpers. Shown in FIG. 42A is a microactuator  260  comprising a rotor  262  and a stator  264 . Connecting the rotor  262  to the stator  264  are compliant springs  266 . Located at a position between the stator  264  and the rotor  262  along the beams  266  is located a patterned epoxy bumper  268 . As shown more clearly in FIG. 42B, the patterned epoxy bumpers  268  are formed so that the bumper  268   a  is located on a top surface of the stator  264 , and extends past a top surface of the stator  264  (as viewed in FIG.  42 B). Similarly, the bumper  268   b  is located on the rotor  262 , and is also patterned on a top surface of the rotor  262 . The bumpers  268   a ,  268   b  are shaped so that the portion of the bumpers  268  that overlap the gap between the rotor  262  and stator  264  are the location of contact should the rotor  262  contact the stator  264 . Thus, the bumpers absorb any such stress that occurs when the two parts of the microactuator come into contact. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the. invention.