that involve structures and processes in the nanometer range, and it is considered a key technology of the 21st century. A

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1 Semiconductor & Metrology INFO Discover the new destination in accuracy. January 2012 Accuracy of Measuring Machines in the Nanometer Range The trend in the semiconductor industry to ever higher levels of integration and, with it, to continuously finer structures, calls for measuring devices with high resolution for positioning to the nanometer in the manufacturing process and in measuring and inspection technology. Measuring error due to guideway influences and thermal expansion, which at present cannot be compensated by computation, can be ascertained by a new measuring device and therefore significantly reduced. To purposefully change something, you must first be able to measure it. Source: Crash Course in Nanotechnology, keynote speech by Dr. Alois Rhiel, February Encoders with high resolution The concept of nanotechnology is used for a number of technologies Contents Accuracy of Measuring Machines in the Nanometer Range Did You Know... RSF s NEW Design of Slim Linear Encoders Results in Many Benefits Technical Tidbits: HEIDENHAIN Offers Various Encoders for Vacuum Applications John Thormodsgard: Total Customer Satisfaction improvement thrives on customer input that involve structures and processes in the nanometer range, and it is considered a key technology of the 21st century. A nanometer is a billionth of a meter (10-9 m) and denotes a limit range in which quantum physical effects begin to play an important role. Nanotechnologies such as those seen in optical and semiconductor manufacturing use machines as well as measuring and testing equipment with high positioning accuracy and repeatability. The specified values lie in the range of 100 nm to 1 nm and even smaller. The encoders in these machines are subject to very stringent requirements for signal quality and accuracy. These requirements are met by laser interferometers or interferential optical encoders as position measuring devices. Both already offer very high resolutions well below 1 nm. Laser interferometers can be simply aligned with the tool center in order to eliminate Abbe continued on next page Did You Know... that over a hundred HEIDENHAIN rotary encoders are in use every day during the extraordinary Le Rêve theater production at the Wynn Las Vegas? The show is set in a one million gallon (water) capacity theater and features acrobatic diving and feats of strength with state-of-the-art special effects. Le Rêve, meaning Dream in French, immerses the audience with a cast of 85 characters into a world of fantasy, adventure, and intrigue. The original cost of the production itself is estimated at $130 million. The aqua theaterin-the-round is truly unique and features an elaborate 84,000 pound automated turntable mounted to the ceiling called the carousel. This carousel is critical in the acrobatic displays in the air, and contains 20 winches which aid in manipulating performers and scenery. The automation system at Le Rêve is comprised of 131 different axes of motion. This includes a system of underwater lifts and high speed winches used to fly the performers and scenery. HEIDENHAIN s precision measurement rotary encoders run on the majority of these axes. The HEIDENHAIN encoders do a very important job here and have been very reliable over the years, explained Shaun Quinn, Head of Automation at Le Rêve. During the show, we have up to 60 winches all moving seamlessly at the same time and it is imperative that they be dead on in order to maintain safety and artistic integrity. We need to have an extreme amount of control, reliability, and repeatability, and between our software and encoders, we do. Quinn continued, The HEIDENHAIN EQN 425 encoders are used in this system not only because of the high accuracy and continued on next page

2 Did You Know... continued from 1 reliability of their sinusoidal incremental signals, but also for the absolute feature which the system uses for redundancy. The absolute aspect also allows for easier maintenance due to no loss of position during power down and startup procedures. For more information on HEIDENHAIN s EQN 425, please go to For show information, visit com and click on Entertainment. Accuracy of Measuring Machines in the Nanometer Range continued from 1 error. One of the most serious disadvantages of these devices, however, is their dependency of the wavelength of laser light on environmental parameters such as temperature and air pressure. These have to be carefully measured along the interferometer s optical path and the error must be continuously compensated. Any fluctuation, be it ever so small, of temperature, air pressure, the composition of air and similar parameters ultimately results in a change in the wavelength of light and leads over a measuring length of 500 mm to position fluctuations in the order of 50 nm. The alignment error of the laser, which changes over time, lead to cosine or Abbe error that has to be calibrated continuously. largely free of harmonics and can be highly interpolated. These encoders are therefore especially suited for high resolution and high accuracy and a very high inherent repeatability. Even so, their generous mounting tolerances permit installation in a wide range of applications. Stable measuring standards normally have a defined thermal behavior and are independent of air pressure fluctuations. In recent years, the LIP, LIF and PP product families from HEIDENHAIN have established themselves as stable measuring standards. The interferential scanning principle behind them exploits the diffraction and interference of light on a fine graduation to produce signals used to measure displacement that are therefore insensitive to air fluctuations. A relative motion of the scanning reticle to the scale causes the diffracted wave fronts to undergo a phase shift: when the grating moves by one period, the wave front of the first order is displaced by one wavelength in the positive direction, and the wavelength of diffraction order 1 is displaced by one wavelength in the negative direction. Since the two waves interfere with each other when exiting the grating, the waves are shifted relative to each other by two wavelengths. This arrangement results in two signal periods from the relative motion of just one grating period. Interferential encoders function with grating periods of, for example, 8 µm, 4 µm and finer. Their scanning signals are 2 Figure 2: Interferential measuring principle Influence of guiding error All linear bearings have angular guiding error (pitch, yaw and roll) and linear guiding error (straightness, flatness). The error typically lies in the range of 5 to 100 µrad or 0.5 to 5 µm. The relevant statistical dispersion of this error is only a fraction of these values and is very small for air bearings. Angular guiding error leads to local tilting and, with an Abbe offset other than zero, to a length offset of the encoder and thereby influences the machine accuracy. continued on page 3

3 Accuracy of Measuring Machines in the Nanometer Range continued from 2 Figure 3: Influence of guiding error Temperature as spoilsport Although increasing temperature within a certain range improves people s well being, temperature fluctuations are true spoilsports for measuring and testing technology in regard to accuracy and reproducibility. Under temperature fluctuation, the accuracy of the system remains limited in spite of expensive designs and materials or additional measures (such as active cooling). Thermally induced geometrical changes of the machine can be mathematically compensated, if only with limitations. The value of temperature measurement via sensor for linear compensation of thermally induced expansion depends upon - the quality of the sensors used - the correct placement (e.g. with inhomogeneous temperature distribution) - the aging of the sensors, and - in addition, calibrated temperature sensors must be continuously monitored and, if required, replaced with sensors with the same properties. Linear motors are also heat sources, especially on fast machines, and can cause thermomechanical deviations. Because of their complex designs, gantry axes require special examination in this regard. The influence of guiding error and thermal changes presents great challenges on the road to nanometer-exact positioning within manufacturing processes and in measurement and testing metrology. A new type of measuring device from HEIDENHAIN can contribute to meeting them. LIF 481 1Dplus Encoder Decades of experience in the field of microstructuring, together with corresponding equipment for scale carrier manufacture and modern structuring and production machines, similar to those found in semiconductor manufacturing, have combined to fulfill the market demand for a quasi two-dimensional measuring device. Besides the usual longitudinal track (x axis) with the interferential graduation of the familiar LIF (4 µm signal period), the LIF 481 1Dplus features an additional y axis track perpendicular to it. This nevertheless does not require eliminating of the reference mark on the longitudinal track. As is usual at HEIDENHAIN, the absolute position on the scale, established by the reference mark, is gated with exactly one measuring step. The glass ceramic ZERODUR is used in a graduation carrier whose expansion coefficient of 0+/- 0.1 x 10-6 K-1 is exact over a large temperature range and is characterized by high resistance to aging. With the appropriate arrangement of two or three scanning heads (Figure 5) the LIF 481 1Dplus linear encoder makes it possible to measure and compensate linear and angular guiding error or the influences of thermal expansion: Figure 4: LIF 481 1Dplus, a new type of encoder with x axis and additional y axis Figure 5: Arrangement with 2 or 3 scanning heads Recording the real-time condition and compensation of the actual measured values contribute significantly to the improvement of positioning accuracy in the nanometer range. These ambitious expectations of the encoder were confirmed with the impressive results of an experiment. Test setup Figure 6 shows an example of the user of 1Dplus scales on a gantry-type milling machine. The x-axis is equipped with two 3 continued on page 4

4 heads HX1, HX2 in an example arrangement of the scales. If the tool center point (TCP) is also aligned in Z to the centers of rotation HX1 and HX2, all Abbe offsets of the x-axis are equal to zero. The heads HY1 and HY2 detect straightness error (y) of the X guideway axis and, to an extent, the influences of thermal expansion. On the Y axis the heads HX3 and HX4 can be used for compensation of straightness errors in the X axis and Abbe error in the X axis. Summary The inherent repeatability of today s interferential encoders with high resolution is far higher than that of interferometers in air. The effective measuring point of technically perfected encoders is stable and is hardly influenced by tilting. Encoders with 1Dplus scales, which feature an additional perpendicular track, contribute to the reduction of Abbe error and the influences of linear guiding errors and thermal expansion. The additional track provides the information required for compensation in the perpendicular direction and for angular correction. Figure 6: Gantry arrangement with LIF 481 1Dplus DR. JOHANNES HEIDENHAIN GmbH Reinhard Kuhn Senior Product Manager Marketing, Electronics Industry Figure 7: Incremental heating X and Y with fast reciprocation (acceleration = 1 g) RSF s NEW Design of Slim Linear Encoders Results in Many Benefits Featuring an innovative new design, RSF releases the new slim profile linear encoder series MSA 700 and 800 tailormade for metrology applications which require protection from contamination. Typical applications for these encoders are optical comparators, and video and vision systems. The main advantages offered by these encoders are generous mounting tolerances, low level backlash and optimized thermal behavior. Central to the innovative design of these new encoders is the reading carriage and reading head connected by a wear-free and maintenance-free magnetic coupling. The carriage is also constrained by a magnet guide that affects the ferromagnetic tapes on the extrusion. Hence, there are no forces that could stress guide parts and no contact points that could prematurely wear. Improving upon old roller 4 bearing or spring coupled encoders, the new magnetic coupling and guide eliminates wear and provides even pressure along the measuring length. This combination allows for generous mounting tolerances without any negative influence on accuracy. An additional benefit of this magnetic coupling is the extremely low backlash, reducing one of the main weaknesses of sealed encoders. The fiber-reinforced sealing lips made of fluororubber (Viton) are wear and coolant resistant, allowing the encoder to operate in harsh environments. High velocities are also possible due to the high degree of rigidity and ideally formed blade area of the reading head. The scale itself is fastened via a flexible adhesive film in the profile, which compensates for the differing linear expansion between the glass and the aluminum. Thus a reproducible continued on page 5

5 RSF s NEW Design of Slim Linear Encoders Results in Many Benefits continued from 4 thermal growth is ensured by symmetrical expansion or shortening of the scale to the profile. Expansion differences between the aluminum profile and machine slide are accommodated by flexible fastening elements. This new MSA 700 and 800 series is defined as sealed incremental linear encoders that have grating pitches of 20, 10, and 8 microns, and come in accuracies of 2, 3 and 5 microns. This makes them the perfect choice for customer applications requiring precision and protection. They have the same mechanical footprint and electrical properties of the MSA 600 series, and can be customized to suit customer specifications. Technical Tidbit: HEIDENHAIN Offers Various Encoders for Vacuum Applications by Kevin Kaufenberg, HEIDENHAIN Product Manager Kevin Kaufenberg Product Manager HEIDENHAIN is highly integrated into the semiconductor and other industries which have been using vacuum technology for certain wafer process steps and other high technology manufacturing and analysis for many years. Realizing that components which operate in vacuum need to have special requirements as far as cleanliness, limited gas exhalation and dealing with heat transfer, HEIDENHAIN offers various encoders for vacuum applications. which provides excellent shielding of the specially coated wires. The circuit board inside the scanning unit has been designed with special PCB material, special adhesives and coatings to limit gas exhalation, all while handling the heat flow of the internal LED, as there is obviously no air to conduct the heat away. These design criteria allow the scanning unit to be baked out to 120 degrees C in order to remove water vapor. All HEIDENHAIN s vacuum encoders are produced in a clean room and, after the accuracy charts are made, they undergo ultrasonic cleaning. This final step completes the manufacturing process and the encoders are packaged into a double-walled bag and flushed with nitrogen to ensure cleanliness. The encoders are then Within HEIDENHAIN s product offering for high vacuum operation are linear encoders that use non- magnetizable materials for the scanning unit to ensure electron beams are not affected in vacuum. There are no labels on the scanning units, and the markings are laser-inscribed to ensure no gas exhalation. Air vents have also been introduced to allow short pump down times. The cable has been changed to a silver-plated copper braiding ready to be installed into a vacuum chamber and provide over 100,000 hours of precise positioning feedback. If you have any questions about these products, please contact us. Kevin Kaufenberg HEIDENHAIN Product Manager

6 Total Customer Satisfaction improvement thrives on customer input By John Thormodsgard, National Sales Manager, Automation, Semiconductor & Metrology Division John Thormodsgard National Sales Manager, Automation, Semiconductor & Metrology Division Positive change was a strong focus for HEIDENHAIN in 2011, and a new initiative aimed at finding ways to better serve our customers was at the top of that list. To do that, HEIDENHAIN implemented a continuous process improvement program that we named Total Customer Satisfaction (TCS). To its credit, we are realizing some very positive improvements. This all started early 2011 with HEIDENHAIN management taking an introspective view of how we might improve our service. One of the steps identified was to improve our listening perhaps summed up as listen twice as much as we talk. TCS is a step in this direction but is also expanded to include a thorough root cause analysis and corrective action process. Complaints or ideas for improvement are documented in a dedicated IT system, processed via the TCS team, implemented, and then communicated. The heart of the TCS initiative is a cross-functional team consisting of employees from each department of our company as well as our upper management. The team meets regularly to discuss any new complaints or suggestions and will determine if improvement can be made through immediate collaboration or if further analysis is needed. Often, TCS suggestions must be assigned to an individual or subset of the full group to research the issue and the processes involved. In such cases, recommendations are made at a later TCS meeting. Because senior management as well as employees from across all functions of the company is represented on the team, improvements can be realized quite quickly. Over time, incremental improvements realized through TCS should have a significant impact in the form of improved processes. Of course, this system only works when we hear from you. Please contact me or anyone else from HEIDENHAIN when you have a complaint or suggestion for improvement. Through TCS, we will strive to improve our service to you. Sincerely, John Thormodsgard CONTACT INFORMATION For more information about HEIDENHAIN and any of the products or services mentioned here, please feel free to contact us. HEIDENHAIN CORPORATION 333 E. State Parkway, Schaumburg, IL