Abstract:
A gyroscope and temperature sensor are formed on a single chip using SOI-MEMS technology. The temperature sensor has an array of resistors to accurately detect the temperature of the gyroscope in temperatures and conditions that can range from extreme heat to extreme cold. The positioning of the gyroscope and temperature sensor on the same chip allow for extremely accurate real-time feedback of the gyroscope&#39;s temperature for utilization by a control system.

Description:
[0001]     The invention described herein may be manufactured, used and licensed by or for the U.S. Government for governmental purposes without payment of any royalties thereon.  
       BACKGROUND OF THE INVENTION  
       [0002]     I. Field of the invention  
         [0003]     The present invention relates to gyroscopes.  
         [0004]     More particularly, the present invention incorporates a stationary three-fold symmetric vibratory rate gyroscope implementation and integrated temperature sensors in a thick-film silicon-on-insulator (SOI), micro electromechanical system (MEMS).  
         [0005]     II. Discussion of the Background  
         [0006]     Small, affordable, and reliable inertial components are required for small diameter precision-guided military weapon systems. Gyroscopes are inertial components or devices that can sense angular rotation and/or rotation rate. The ring laser and interferometric fiber optic gyroscopes dominate the current tactical missile system market. Although these gyroscope technologies meet most inertial requirements, they tend to be moderately expensive. Recent advancements in microelectromechanical systems (MEMS) technologies make it possible to develop miniaturized, low cost angular rate sensors. The process technologies initially developed for fabricating integrated circuits have now evolved to allow development of MEMS devices.  
         [0007]     Although many organizations are developing MEMS gyroscopes for a variety of applications, most do not begin to address the demanding and challenging requirements for military combat systems. Requirements for small precision guided weapons were the basis for the MEMS gyroscope development criteria. Rate sensing in many small diameter missile guidance units typically requires a rate resolution of 10°/hr. Additionally, for a particular guided munition, a large roll rate about its longitudinal axis may be experienced during flight. The anticipated rotational rates encompass a range of −3000° to +3000°/sec, resulting in a dynamic range of 10 7 .  
         [0008]     In order to control the heading of this system during flight, the system must know its roll angle about the longitudinal axis so that the control systems can adjust accordingly. Therefore, the accuracy of this angular measurement must correspond to a bias stability of 10°/hr in order for the guidance system to compensate.  
         [0009]     Furthermore, actuators in the control system of the guided munition may result in a substantial vibration environment. Large shocks of greater than 1000 G&#39;s can be seen at frequencies ranging from 5 kHz to 15 kHz. Additionally, the inertial device must operate through military temperature environments (−55° to +125°). The criteria for achieving superior resolution while measuring large rotation rates adds difficulty to design determination since there are tradeoffs that exist in determining the mechanical structure&#39;s topology.  
         [0010]     For example, achieving superior resolution requires substantial inertial mass available in the device. However, when a large mass design is devised, the resulting deflections due to large values of rotational rate are generally more than the device can accommodate. In most cases, enough electrostatic feedback force cannot be produced to counter the Coriolis forces. Given that the MEMS gyroscope must not only survive but operate through these harsh environments, the challenge has been to develop a robust, accurate and reliable MEMS gyroscope.  
         [0011]     MEMS angular rate sensors or gyroscopes that detect angular rate utilize the Coriolis Effect. A vibratory rate gyroscope is a sensor that detects and measures rotation by generating and measuring Coriolis acceleration. In other words, the sensing method used in a vibratory rate gyroscope is based on the Coriolis pseudo-force resulting from a translating body in a rotating frame of reference. The conventional illustrations of  FIG. 1  and  FIG. 2  demonstrate the Coriolis Effect on an object.  
         [0012]     A mass, m, is moving at time, t, with a velocity v x  along both the (x, y) and (x′,y′) axes.  
         [0013]     At time t+dt, the (x′, y′) axes have rotated Ωdt where Ω is the rotational rate. In accordance with Newton&#39;s Laws, the mass is still moving with velocity v x  in the (x,y) frame of reference.  
         [0014]     However, in the (x′,y′) frame of reference, it appears that the velocity, v x  has moved by an amount dv x . Therefore the Coriolis acceleration and force is:  
             a   =         ⅆ   v       ⅆ   t       =       -   2     ⁢   Ω   ⁢           ⁢     v   x                 Equation   ⁢           ⁢     (   1   )                 F   =     ma   =       -   2     ⁢   m   ⁢           ⁢   Ω   ⁢           ⁢     v   x                 Equation   ⁢           ⁢     (   2   )               
 
         [0015]     The fundamental result from this simple derivation of system dynamics is that a translating mass in a rotational frame of reference will appear to experience, within the rotating frame, a force orthogonal to its velocity and proportional to its velocity and the rate of rotation of that frame of reference.  
         [0016]     The conventional vibratory rate gyroscope consists of a mass-spring system that has at least two orthogonal modes of oscillation ( FIG. 3 ). The mass is forced to have an oscillatory velocity in the frame of reference of the device along the x-axis. Anchored springs  16  and  14  having respective identical spring constants k x  and k y  are attached to respective rollers  20  and  18  so as to provide a suspension that constrains the mass to particular orthogonal oscillation modes. When the device experiences rotation, the Coriolis force induces oscillation of the orthogonal mode of the device. Sensors detect this motion and provide a signal from which the rotational rate is extracted. The Coriolis force is proportional to the external rotation rate.  
         [0017]     The equations of motion for a mass-spring system moving in a non-inertial reference frame are found using Lagrangian dynamics. Expressions for the potential energy and kinetic energy of the system must be derived first.  
         [0018]     The global frame of reference is the p-q-α frame, the local frame of reference x-y-φ is rotated by an angle θ with respect to the global frame. The local frame is also translated by r x  and r y  with respect to the global frame.  
         [0019]     The potential energy stored in the springs is:  
             PE   =         1   2     ⁢     k   x     ⁢     x   2       +       1   2     ⁢     k   y     ⁢     y   2       +       1   2     ⁢     k   ϕ     ⁢     ϕ   2                 Equation   ⁢           ⁢     (   3   )               
 
         [0020]     The kinetic energy is calculated in the global frame of reference, using the global variables:  
             KE   =         1   2     ⁢       m   ⁡     (       ⅆ   q       ⅆ   t       )       2       =         1   2     ⁢       m   ⁡     (       ⅆ   p       ⅆ   t       )       2       +       1   2     ⁢       I   ⁡     (       ⅆ   α       ⅆ   t       )       2                   Equation   ⁢           ⁢     (   4   )               
 
         [0021]     The global variables are related to variables in the local frame of reference by rotation matrices: 
 
 q ( t )=cos(θ) x ( t )−sin(θ) y ( t )+ r   x ( t )  Equation (5) 
 
 p ( t )=sin(θ) x ( t )+cos(θ) y ( t )+ r   y (t)  Equation (6) 
 
α( t )=θ( t )+φ( t )  Equation (7) 
 
         [0022]     The equations of motion in the local frame of reference are found from  
               F     x   i       =         ∂   L       ∂     x   i         -       ⅆ     ∂   L           ⅆ   t     ⁢     ∂     x   i                     Equation   ⁢           ⁢     (   8   )               
 
         [0023]     Where x i  are generalized coordinates, F x , are external forces such as damping and excitation forces, and L is the Lagrangian (L=KE−PE).  
         [0024]     The global coordinates in the kinetic energy relation are substituted by Equations (5), (6) and (7) to convert to local coordinates. Equation (8) is then applied for each of the on-chip coordinates (x, y, φ), by replacing the generalized coordinate by the respective on-chip coordinate, yielding:  
                     x   ..     =       ⁢         -     ω   x   2       ⁢   x     -         ω   x     Q     ⁢     x   .       -       F   x     m     +     x   ⁢           ⁢     Ω   2       +                     ⁢       y   ⁢           ⁢     Ω   .       +     2   ⁢   Ω   ⁢           ⁢     y   .       -       a   x     ⁢   cos   ⁢           ⁢   θ     -       a   y     ⁢   sin   ⁢           ⁢   θ                     Equation   ⁢           ⁢     (   9   )                         y   ..     =       ⁢         -     ω   y   2       ⁢   y     -         ω   y     Q     ⁢     y   .       -     2   ⁢   Ω   ⁢           ⁢     x   .       +     y   ⁢           ⁢     Ω   2       -     x   ⁢           ⁢     Ω   .       +                     ⁢         a   x     ⁢   sin   ⁢           ⁢   θ     -       a   y     ⁢   cos   ⁢           ⁢   θ                     Equation   ⁢           ⁢     (   10   )                   I   ⁢           ⁢     ϕ   ..       =         -     k   ϕ       ⁢     ϕ   .       -     I   ⁢           ⁢   ϕ               Equation   ⁢           ⁢     (   11   )               
 
         [0025]     Where ω x   2 =k x /m and ω y   2 =ky/m are the resonant frequencies of the x and y modes, respectively, a x  and a y  are external accelerations, and Q is the quality factor of resonance. The Coriolis accelerations are the 2 Ω{dot over (y)} and 2 Ω{dot over (x)} terms. The last two terms in Equations (9) and (10) are the acceleration terms, which create transients at the natural frequency of the system. The terms yΩ and xΩ refer to the inertia of angular acceleration. The terms yΩ 2  and xΩ 2  are centripetal accelerations, and act as spring softeners.  
         [0026]     The importance of the above derivation is that it includes extra terms in the equations of motion beyond the standard Coriolis force terms. When experiencing large rotational rates and angular accelerations, these extra terms, the centripetal acceleration, linear acceleration and angular accelerations, play larger roles in the error terms of the rotational rate signal.  
         [0027]     In addition, the derivation shows, as is commonly known, the role of matching resonant frequencies so that the benefits of a high quality factor can be applied to the sensor.  
         [0028]     The coefficients in the above equations, particularly the spring constant and quality factor, are dependent on temperature. In prior art systems, the temperature sensors are prone to sense temperatures at variance from the actual temperature of the gyroscope. Such a result causes errors in the rotational calculations.  
         [0029]     In micro-electronic designs, the proof mass of the gyroscope is positioned and moves above a base substrate surface. Even when experiencing high G forces, the proof mass must remain above the substrate surface.  
       SUMMARY OF THE INVENTION  
       [0030]     Accordingly, one object of the invention is to provide a gyroscope having a temperature sensor that accurately conveys the actual temperature experienced by the gyroscope.  
         [0031]     Another object of the invention is to provide a gyroscope that has a proof mass support structure that prevents the proof mass from touching the base substrate even when subjected to high G forces so as to prevent failure of the device.  
         [0032]     Still another object of the present invention is to provide a SOI-MEMS gyroscope having a superior dynamic range capability.  
         [0033]     Yet another object is to provide a SOI-MEMS gyroscope that is economical to manufacture.  
         [0034]     These objects are provided by a SOI-MEMS gyroscope having a proof mass that is suspended over a base substrate surface by a three-fold suspension that prevents the proof mass from touching the base substrate surface even when exposed to 10,000 G&#39;s of force. The symmetry is three fold in that the device is symmetric along the x and y axes and along its diagonal.  
         [0035]     When x-axis oriented actuators are excited in one mode, rotations of the device about the z-axis result in oscillations in the orthogonal mode that are detected by y-axis oriented sensors. The mode-decoupled suspension allows only one degree of in-plane freedom for each excitation actuator, thereby attenuating errors due to oscillation axis misalignment.  
         [0036]     In addition, suspension symmetry maintains matched oscillation mode frequencies through process and temperature variations, allowing maximized dynamic range in a wide dynamic range discrete-time control loop.  
         [0037]     The three-fold symmetric gyroscope implementation inherently matches the resonant frequencies in both oscillation modes by using completely symmetric suspension, thereby increasing the sensitivity of the device by using the Q-factor to maximize displacements for a given force. Also, the symmetry reduces the effects of process variations on the device sensitivity. In practical implementation of the vibratory rate gyroscope, the designed Q value is constrained by the necessary bandwidth of the input rotation.  
         [0038]     The scale factor of the device is highly dependent on the matching of the resonant frequencies, since Q is an important gain. If the frequencies are not matched, only a fraction of the Q will be seen as gain. Through time and temperature variations, changes in the modes of the SOI based MEMS vibratory rate gyroscope should match so as to prevent the scale factor from drifting.  
         [0039]     The suspension of the present invention utilizes a folded-beam concept (the multiple strips of the present invention can be viewed as folded beams of the flexure system). Folded flexures exhibit much less nonlinearity than a single straight flexure. A one-piece straight beam when deflected orthogonal to the longitudinal axis will experience stretching along that axis. This stretching increases the actual spring constant and adds nonlinear terms.  
         [0040]     By contrast, in the folded flexure suspension of the present invention, both the anchor holding the strips in place, and the force applied to the strips or flexure are co-linear. As the strips flex, there is no stretching thereby allowing larger linear displacements. In total, folded flexures (the multiple strips of the present invention) provide for increased linear response, reduced angular moments, and decreased cross-talk over the entire dynamic range.  
         [0041]     Even with the three-fold symmetric gyroscope configuration, induced drifts occur as a result of the silicon material being exposed to extreme temperatures. Accordingly, these temperature drifts are remedied by accurate measurements of chip temperature that is conveyed in real time to control electronics.  
         [0042]     The accurate measurement of chip temperature is provided by an array of resistor elements that comprise a temperature sensor that is positioned next to the gyroscope and on the same chip substrate. This allows the gyroscope and temperature sensor to be made during the same manufacturing process. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0043]     A more complete appreciation of the drawings and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the following drawings, wherein:  
         [0044]      FIG. 1  and  FIG. 2  are prior art graphical illustrations of a mass experiencing a corriolis force;  
         [0045]      FIG. 3  is a prior art graphical illustration of a mass-spring system having two orthogonal modes of oscillation;  
         [0046]      FIG. 4  is a conceptual mass-spring system of a proof mass at rest;  
         [0047]      FIG. 5  is a graphic demonstrating the direction of the sensed mode and driven mode for  FIGS. 4, 6 ,  7  and  8 .  
         [0048]      FIG. 6  is the conceptual mass-spring system of  FIG. 5  in a driven mode;  
         [0049]      FIG. 7  is a conceptual SOI-MEMS multiple mass-spring system at rest that is analogous to  FIG. 4 ;  
         [0050]      FIG. 8  is a conceptual SOI-MEMS mass-spring system in a driven mode that is analogous to  FIG. 6 .  
         [0051]      FIG. 9  is a perspective illustration of a SOI-MEMS gyroscope according to the present invention;  
         [0052]      FIG. 10  is a top view of the single-substrate gyroscope and temperature sensor according to the present invention;  
         [0053]      FIG. 11  is a side-view of a 100 micron silicon substrate on a 1 micron oxide SOI wafer as used in manufacturing the present invention;  
         [0054]      FIG. 12  is a side-view showing that the 100 micron silicon substrate layer of  FIG. 11  is applied and patterned by photoresist;  
         [0055]      FIG. 13  is a side-view showing how the 100 micron layer of  FIG. 12  is subjected to a Si reactive ion etch and strip photoresist;  
         [0056]      FIG. 14  is a side view showing that the 100 micron layer of  FIG. 13  is subjected to an isotropic oxide etch to release microstructure;  
         [0057]      FIG. 15  is a side-view showing that 100 micron layer of  FIG. 14  is selectively provided with a metal layer to provide for electrical contacts;  
         [0058]      FIG. 16  is a sectional perspective view of the SOI-MEMS gyroscope of the present invention in which a 1 micron gap  70  exists between the 100 microns of silicon between points AA and BB and the silicon base substrate located between points CC and DD;  
         [0059]      FIG. 17  is a perspective view of the gyroscope according to the present invention which demonstrates the central and lateral flexures that support the proof mass above the base substrate;  
         [0060]      FIGS. 18 and 19  are top view of the proof mass and central and lateral flexures according to the present invention;  
         [0061]      FIG. 20  is a side-view of a straight resistor element of the heat sensor according to the present invention;  
         [0062]      FIG. 21  is a top-view of a folded resistor element of the heat sensor according to the present invention;  
         [0063]      FIG. 22  is a side-view of a portion of the folded support area of the resistor element of  FIG. 21 ;  
         [0064]      FIG. 23  is a schematic illustration of the folded support region of  FIG. 21 ;  
         [0065]      FIG. 24  is a perspective illustration of a serpentine resistor element being supported on a silicon substrate according to another embodiment of the present invention; and  
         [0066]      FIG. 25  is a perspective illustration of a plurality of gyroscopes and a corresponding plurality of sensor elements all arranged on a single substrate. 
     
    
     DETAILED DESCRIPTION  
       [0067]     In a vibratory gyroscope, the two fundamental modes of oscillation are along the x-axis, the driven mode, and along the y-axis, the sensed mode ( FIG. 5 ).  
         [0068]     A conceptual suspension, shown in schematic form in  FIG. 4 , approximates a set of identical springs  26 ,  24  placed symmetrically about a central mass. The springs  26 ,  24  are connected to respective rolling pins  28  and  30  that allow the mass to move and slide in the y and x directions.  
         [0069]     In  FIG. 6 , the actual deflection of the mass in x and y is shown. The rolling pins  28 ,  30  constrain the springs to act along the x-axis or the y-axis, only. In that the mass of  FIG. 6  has moved to the right and downward from its position in  FIG. 4 , the spring  24  is compressed against anchor  22 . Spring  27  is likewise compressed from the mass&#39; movement in the y direction while springs  26  and  25  are stretched.  FIGS. 4 and 6  demonstrate that the restoring forces on the mass are always orthogonal and in line with the x- and y-axes.  
         [0070]     In an analysis of the conceptual schematic of  FIG. 6 , F x  represents the forcing function. If the forcing function, F x , is at the resonant frequency of the driven mode, then the displacement of the proof mass is maximized, with a gain Q over the static displacement. The frequency of the Coriolis force F c  is equal to the resonant frequency of the driven mode, with amplitude modulated by both maximum displacement of the mass x and the rate of external rotation.  
         [0071]     The velocity of the excited mode, the size of the mass, and the external rotation rate determine the magnitude of the Coriolis force. If the resonant frequency of the sensed mode is equal to that of the driven mode, the maximum displacement for a given rotational rate will occur in the sensed mode.  
         [0072]     In development of the present invention, the concept depicted in  FIGS. 4 and 6  was taken to formulate a conceptualization of a SOI-based MEMS vibratory rate gyroscope chip ( FIGS. 7 and 8 ).  
         [0073]     In  FIGS. 7 and 8 , the central proof mass  34  is surrounded by a symmetric suspension having identical springs sets  24 A,  25 A,  26 A,  27 A,  37 ,  39  along both the x and y modes. The comb-finger actuators  40 ,  41  apply an electrostatic force to the proof mass in the x-direction thereby exciting the driven mode so as to allow the proof mass to move above the base substrate surface  38 . The comb-finger actuators  40  and  41  are provided with rollers  33 .  
         [0074]     When experiencing an external rotation rate, the Coriolis force acts along y and has a frequency equal to that of the excitation frequency. The Q-factor of the system provides a gain in the displacement of the sensed mode. The y deflection is sensed with a pair of comb-finger capacitors  42 ,  43  that are connected as a differential capacitive voltage divider. The comb-finger capacitors  42 ,  43  are provided with rollers  33 .  
         [0075]     The spring  26 A in  FIG. 7  may be thought as being analogous to the spring  26  of  FIG. 4 . Likewise compressed spring  24 A of  FIG. 8  may be thought as being analogous to compressed spring  24  of  FIG. 6 . As the proof mass  34  moves from its position in  FIG. 7  to the position of  FIG. 8 , springs are compressed and stretched in similar fashion to those of  FIG. 6 .  
         [0076]     The suspension of the conceptualized MEMS vibratory rate gyrocope of  FIGS. 7 and 8  is three fold symmetric. By “three fold symmetric”, it is meant that there is symmetry along y, along x and along the device diagonal.  
         [0077]     The suspension serves two purposes. First, the driven and sensed modes of the device displace different, but identical, spring sets; one set displaces in x and one set displaces in y. Spring constants as well as moving mass are matched along both the excitation and sense modes.  
         [0078]     Therefore, both oscillation modes have equal resonant frequencies. The modes will theoretically match even if a uniform process variation occurs, e.g., over-etching of the proof mass. This matching will remain through time and temperature variations.  
         [0079]     The second purpose of the suspension is to decouple, mechanically, the x and y deflections of the actuators and sensors. The suspension allows motion of the central mass in both x and y using complete springs that are very stiff in one direction and very compliant in the other. The masses that attach to the actuators and sensors are placed in the suspension in such a way that they can only move along one axis. Thus, a deflection of the proof mass  34  in x will not affect the comb-sensor  42  which only moves in y. Therefore, the spring network reduces the mechanical cross-talk between the sensors and actuators.  
         [0080]     The suspension is made up of simple folded beam springs. In both the x and y directions, there is a total of 6 springs per direction, resulting in a total spring constant for each mode of:  
         k   x     =           6   ⁢   Eh   ⁢           ⁢     ω   x   3         l   x   3       ⁢           ⁢     k   y       =       6   ⁢   Eh   ⁢           ⁢     ω   y   3         l   y   3             
 
 , where h is the thickness of the beam, w x  and w x , are widths of the beams along x and the beams along y, respectively, and l x  and l y  are the lengths of the beams along x and beams along y, respectively. 
 
         [0081]     The comb-drive actuators in the device can produce a force, F d , and a displacement in the excited mode, x e , of:  
         F   d     =       1.14   ⁢   N   ⁢           ⁢     ɛ   o     ⁢     hV   2         g   o           
              x   e          =       QF   d       k   x           
 
 , where g o  is the gap between fingers of the comb-drive, N is the number of fingers, h is the thickness of the fingers, and V is the voltage across the actuator. The factor of 1.14 accounts for nonideality of the actuator due to fringing fields. 
 
         [0082]     The resonant frequency of the sensed mode (and hence the driven mode) is:  
         ω   ry     =           k   y     m       =     ω   rx           
 
         [0083]     One can predict the magnitude of the sensed displacement, y, given the mass, m, the modes resonant frequency, ω ry , the external rotation rate, Ω, the Q-factor of resonance, and the spring constants. That mechanical sensitivity is then  
           y   Ω          =       2   ⁢     mQ   2     ⁢     ω   r     ⁢     F   d           k   x     ⁢     k   y             
 
         [0084]     Brownian noise will place a limit on the resolution of the device. This noise can be estimated with the following equation [14] 
           F   _     n   2     =       4   ⁢   kT   ⁢           ⁢     ω   r     ⁢   Δ   ⁢           ⁢   f     Q         
 
 , which will represent a noise in the rotational rate signal of [3] 
         Ω   n     =         kT   ⁢           ⁢   Δ   ⁢           ⁢   f       mQ   ⁢           ⁢     ω   r     ⁢     x   2               
 
         [0085]     These equations can be used to size the gyro geometries for specific rate ranges, sensitivity, and resolution requirements.  
         [0086]     Much experimentation was required to progress from the conceptual (SOI-based) MEMS vibratory rate gyroscope of  FIGS. 7 and 8  to the operable device of the present invention.  
         [0087]     With reference to  FIG. 9 , the silicon-on-insulator-based (SOI-based) MEMS vibratory rate gyroscope  50  of the present invention is a single layer structure having a proof mass  52  that is placed in a three-fold decoupled symmetric suspension with matched fundamental oscillation modes. The suspension includes four central flexures  60 A,  60 B,  60 C and  60 D and eight lateral flexures  62 A,  62 B,  62 C,  62 D,  62 E,  62 F,  62 G,  62 H.  
         [0088]     Lateral flexures  62 A and  62 H are anchored by lateral anchor  68 A. Lateral flexures  62 F and  62 G are anchored by lateral anchor  68 B. Lateral flexures  62 E and  62 D are anchored by lateral anchor  68 C and lateral flexures  62 C and  62 B are anchored by lateral anchor  68 D. Anchor (stator)  54 B is connected to sensor  56 B, and anchor (stator)  54 A is connected to sensor  56 A. Sensors  56 A and  56 B are comb-finger capacitors. Anchor (stator)  64 A is connected to comb-finger actuator  58 A and anchor (stator)  64 B is connected to comb-finger actuator  58 B. Electrical connections such as connector  67  connect the comb-finger actuators to bond sites such as bond sites  66 A,  66 B. A transimpedance amplifier (not shown) can be utilized to detect the currents in the capacitive divider of the sensed comb-finger capacitors and the currents in the drive off-chip electronics. The detected data is provided to a CPU or control part the missile control system.  
         [0089]     The device is fabricated in a cost effective and highly controllable process for in-plane inertial sensors. In  FIG. 11 , the process begins with a silicon-on-insulator wafer having a 100 μm thick silicon layer  204  on top of a 2 μm or 1 μm thick oxide layer  202 . A silicon base layer or standard silicon handle wafter  200  lies below oxide layer. In  FIG. 12 , a metal layer  206  of gold, silver or other appropriate metal is deposited and patterned to yield electrical contracts.  
         [0090]     Then, in  FIG. 13 a  thick photoresist mask  208  is patterned on the wafer using standard lithography. This layer protects the metal during subsequent steps, and also devises the geometries of the device structures. Thereafter, in  FIG. 14 , deep Silicon Reactive Ion Etching (Si RIE) is used to define the microstructure by etching away the oxide layer  202 E.  
         [0091]     After the deep etch and removal of photoresist, the device undergoes a sublimation-based release process ( FIG. 15 ) so as to release given structures  209  with a post release anti-stiction coat that reduces process induced and in-use stiction.  
         [0092]     After release, metallization is evaporated on the surface to create electrical contacts. The mechanical structure is integrated in a vacuum-sealed hermetic package with a separate CMOS readout ASIC.  
         [0093]     In  FIG. 16 , a sectional view is present to demonstrate that the proof mass  52  is suspended above the base substrate surface  70  such that the distance from BB (a point on the bottom of the proof mass  52  to CC (a point on the base substrate top surface) is 1 or 2 μm.  
         [0094]     With reference to  FIG. 17 , the proof mass  52  is provided with holes  53  which are utilized during the fabrication process to allow chemicals to pass through to the base substrate surface  70 . A lateral anchor  68  connects to a lateral flexure  62 . The central flexure  60  has a strip connector or truss  100  integrally connected to four strips of the central flexure that are attached to the central part  80  of flexure support (rotor)  78 . Flexure support (rotor)  78  connects to a row of fingers  59  of the comb-finger actuator  58 . The fingers are cantilevered to the flexure support  78 . A second row of fingers  57  is cantilevered to the anchor (stator)  64  at a front edge  67  of the anchor. In such a manner the comb-fingered actuators  58 A,  58 B and comb-fingered sensors  56 A,  56 B are positioned around the periphery of proof mass  52 .  
         [0095]     With reference to  FIGS. 18 and 19 , the central flexure  60  is provided with flexure strips  102  and  106  that connect flexure support  78  to strip connector  100 . Central flexure  60  futher includes flexure strips  104  and  108  that extend from strip connector  100  toward the flexure support  78 , but do not contact flexure support  78 . Instead, strips  104  and  108  connect to lateral isthmus  69 A and lateral isthmus  69 B, respectively. Lateral isthmus  69 A connects to promontory region  112 A of proof mass  52  and lateral isthmus  69 B connects to promontory region  112 B of proof mass  52 . Strip connector  100  is positioned proximate to but does not touch the central interior border  91  of the proof mass  52 . Strips  102  and  106  extend from strip connector  100  to the central part  80  of flexure support  78 .  
         [0096]     The flexure support (rotor)  78  provides support for a central flexure and two lateral flexures on each side of the central flexure  60 . The flexure support  78  extends laterally on both sides of its central region  80  to form lateral support regions  83 . From the lateral support region  83  an isthmus strip  76  connects to strip  96 .  
         [0097]     Strips  88  and  92  are positioned in the middle region of the lateral flexure and are integrally attached to an anchor  68 . A narrow channel  90  extending to the base substrate surface separates strips  88  and  92 . Strip  94  is connected to strips  96 ,  88  and  92  by an orthogonal connector  99  that is proximate to but does not touch a connecting region  82  which connects the central part  80  of flexure support  78  with a support arm  72 . An isthmus  74  connects the support arm  72  with strip  94 . Strips  96 ,  88 ,  92  and  94  are all parallel to one another.  
         [0098]     Still with reference to  FIGS. 18 and 19 , the prototype gyroscope of the present invention had a proof mass that measured 1770 μm across. The side border regions  110 A,  110 B measured 555 μm in length. The promontory regions  112 A,  112 B measured some 240 μm in length and 45 μm in width. A distance of some 52 μm separated the strip  96  from strip  88  and the same 52 μm separated strip  92  from strip  94 . Strips  96 ,  88 ,  92  and  94  measured about 8 μm in width and had a length of approximately 422 μm. Orthogonal connector  99  had a width of 8 μm as well. Strips  104 ,  102 ,  106  and  108  had a length of approximately 420 μm and measured 8 μm across. Strip  104  was separated from promontory  112 A by a distance of 28 μm. A distance of some 30 μm separated the central interior border  91  of proof mass  52  from strip connector  100 .  
         [0099]     The strips  96 ,  88 ,  92 ,  94  of lateral flexures  62  and the strips  104 ,  102 ,  106  and  108  of the central flexures  60  may be viewed as forming folds with gaps lying between the respective strips. Respective gaps separate the strips  96 ,  88 ,  92 ,  94  from the support arm  72 , connecting region  82  and lateral strip  83  of flexure support  78 . A gap separates the connecting region  82  of flexure support  78  from the promontory region  112  of the proof mass. A gap separates the side border  100  of the proof mass from the support arm  72  of the flexure support  78 .  
         [0100]     With reference to  FIG. 10  and  FIGS. 20-22 , a temperature sensor  118  is provided on the same base substrate surface as the gyroscope  50 . In this manner the temperature detected by the temperature sensor will more accurately convey the actual temperature experienced by the gyroscope. Further, the temperature sensor can be formed during the same manufacturing process as the gyroscope. The temperature sensor has an array of resistors of various lengths and types.  
         [0101]     The integrated temperature sensor in  FIG. 10  includes folded silicon resistor bridges. The resistors exhibit a temperature dependent resistance. These are measured by applying a DC current level and monitoring voltage across the bridge. An array of folded bridges of various lengths and straight sensors of various lengths are provided to more accurately detect temperature in varying temperature ranges.  
         [0102]     A folded resistor  120  of an array of resistors  125  is provided with beam regions  132 A and  132 B that connect at one end to an electrical contact  135 . The other end  130  of the beams  132 A and  132 B is a folded region that is supported by an insulation layer of oxide  160  that is left behind after the etch and release step of the manufacturing process.  
         [0103]     The side view of the region  150  of  FIG. 21  is demonstrated in  FIG. 22 .  FIG. 22  and  FIG. 23  demonstrate that the folded end region is three times thicker than the support beams. This construction gives proper support and prevents the beams  132 A,  132 B from touching and shorting out on the underlying base substrate surface  70 .  
         [0104]     For the integrated temperature sensors, the sensitivity of the resistor bridges to temperature is an important factor. The resistivity of the starting material (ρ) was defined as 0.1 ohm-cm and the thickness (t) was defined to be 100 μm. Sheet resistance is defined as:  
         R   s     =     ρ   t         
 
 and given in units of ohms/square. The resistance of a resistor is then defined as  
       R   =       R   s     ⁡     (     L   W     )           
 
 where L is defined as the length and W is defined as the width of the trace. Some of the integrated resistors used in the current embodiment are straight like the one depicted, but others are folded and serpentine versions. 
 
         [0105]     To calculate the resistance change due to temperature the following equation is used 
 
 R=R   0 (1+α( T−T   0 )) 
 
 where α is defined to be the temperature coefficient of resistance (TCR), T is the temperature, T 0  and R 0  are the temperature and resistance references respectively. 
 
         [0106]     T 0  is defined to be 300K. The TCR for silicon of this doping level has been experimentally measured as 2.5E-03 K −1 . In calculating the total resistance two factors must be considered (1) the resistance due to the bridge and (2) the resistance due to any corners in the layout.  
         [0107]     For all of the folded resistor bridges, a turn is required in order to line up the bond pads with the periphery of the chip. This turn must be accounted for when calculating resistance.  
         [0108]     To prevent accidental shorting due to long unsupported beams touching the handle of the wafer, all ends of the beams are anchored. This requires a corner configuration as shown in  FIG. 23 .  
         [0109]     The integrated temperature sensors ( FIG. 10 ) provide a real-time and accurate measurement of temperature right on the MEMS chip. This is important in maintaining gyroscope performance when exposed to extreme temperature conditions.  
         [0110]     The array of integrated temperature sensors provide accurate temperature data and can be manufactured on the same chip and at the same time as the gyroscope components without extra processing steps or external integration thereby greatly reducing manufacturing costs. In  FIG. 24 a  serpentine resistor  142  having a serpentine beam  140  is supported by contacts  139 A,  139 B.  
         [0111]     The SOI-MEMS technology utilized by the present invention allows hundreds of complementing gyroscopes  50 A,  50 B,  50 C, etc., and temperature sensors  118 A,  118 B,  118 C, etc. to be manufactured on the same chip with readout of information being sent to control electronics or CPU  175 .  
         [0112]     From the above description those skilled in the art will recognize that various modifications and embodiments may be made without departing from the spirit of the invention. Accordingly, the scope of the invention is to be limited only by the claims appended hereto.