We released a vacuum robot that achieves the industry’s fastest transfer level (650WPH), making a significant contribution to improvements in semiconductor productivity.

Semiconductor wafer transfer robot “UT-VDW3000” realizes the world’s fastest level of high-speed transfer

For the UT-VDW3000, direct drive motors is mounted on the robot arm and the rotation axis, and steel belts and high-friction pads are adopted for the transmission of arm extension/retraction and on the hands.
By significantly reducing vibration when the robot is operating at high speed and suppressing wafer slippage to the minimum extent, the world’s fastest level of high-speed transfer at “650WPH*” has been realized under vacuum environments.
The higher-speed wafer transfer contributes to improvements in semiconductor productivity.
*The number of wafers processed per hour is 650.

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Adoption of direct motors without using gears to eliminate vibration source

A speed reducer connected with a small servomotor can increase the power output, but vibration occurs when the gears are engaged during rotating operation. The amount of vibration may not pose a problem when general objects are gripped and transferred, but it will cause problems during wafer transfer in vacuum, such as wafer slippage and particle generation. Therefore, for wafer transfer in vacuum, driving only with a motor without using a speed reducer leads to significant reduction in vibration.

Vibration comparison between models with/without a speed reducer

In a vacuum robot, if vertical vibration is transmitted to wafers during operation, frictional force will be lost, and the wafers will easily slip. On a robot equipped with a speed reducer, vertical vibration occurs due to the engagement of the gears during operation.
However, a robot equipped with a direct drive motor that secures the torque required to drive the robot requires no speed reducer and no vertical vibration occurs, though the size of the drive source becomes large.

■Measurement chart of
vertical vibration on
the hand on which wafers
are placed during robot operation

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Significant simplification of teaching work reduces work hours.

The accessing target of an object transferred is a FOUP in which multiple wafers are stored or the stage on which one wafer is placed. Teaching work of the target stage is simply performed by one point, and even when the target is a FOUP, teaching work can be completed by only a few points.

Teaching points of the target station are reduced from 5 to 1.

For placing/removing wafers into/from process equipment, there are five transfer points (RB, EB, EM, ET, and RT).

【Robot motion in vacuum】
・Removing a wafer: RB → EB (arm extension) → EM (the Z-axis ascends to the wafer contact position) → ET (the Z-axis further ascends to the position where the wafer is lifted up completely) → RT (arm retraction to the HOME position)
・Storing the wafer: Implement the removing operation in reverse order（RT › ET › EM › EB › RB）

● Problem in teaching work

• ・With standard robot controllers, teaching is performed on all five points (RB, EB, EM, ET, and RT).
• ・There are also cases where teaching is performed on intermediate positions between RB and EB and between ET and RT.

→ There is a problem that teaching work requires a significant amount of time.

● Countermeasures

• ・ The developed vacuum robot is a cylindrical coordinate type, and the arm extension/retraction stroke and the positions of the rotation axis (θ-axis) and the ascending/descending axis (Z-axis) are fixed by teaching the transfer position (EM).
• ・For the amount of the Z-axis ascent from EB to EM, which is pre-registered by parameters, no teaching work is required.
• ・Similarly, no teaching work is required for EM → ET.
• ・For ET → RT, a simple return is made on the arm axis (R-axis) to the HOME position, and no teaching work is required.

Actual teaching work

・Move the arm into the process equipment and simply perform teaching work at the EM position.

The teaching position in the cylindrical coordinate system is EM (R, θ, Z). Assuming that the amount of the Z-axis ascending/descending in the process equipment is α, other teaching points are EB (R, θ, Z-α), ET (R, θ, Z+α), RB (0, θ, Z-α), and RT (0, θ, Z+α).

・Teaching work is reduced as it is completed in only one place per process equipment.

Control command interface dedicated to semiconductor wafer transfer

Wafers are transferred by the motion commands sent from the robot-mounted process equipment controller to the robot controller.
Between the process equipment controller and robot controller, serial communication via a LAN is commonly used.
For operating the robot, the content of serial communication messages is defined.
Rules in the table below are set to determine whether to remove or store wafers, at which station, in which slot, and with which arm to execute commands.

Definition of the message format

The format of messages sent via a LAN is defined in the order of motion command no. at the head, station no., slot no., and arm selection.

Motion (1): When the following message is sent from the equipment to the robot side, the robot performs the motion to get a wafer in the first slot of station no. 5 with the right hand.

Motion (2): By the execution of the following message, a wafer is placed in the first slot of station no. 5 with the left hand, and replacement of wafers is completed.

■Details of the motion performed when each command is executed

Motion (1): The θ-axis and Z-axis move to the RB position of the right hand of station no. 5. After that, the arm extends to the EB position, and the Z-axis ascends to EM and further to ET. Finally, the arm retracts to the RT position, when the motion of the command is finished.

Motion (2): The θ-axis and Z-axis move to the RT position of the left hand of station no. 5. After that, the arm extends to the ET position, and the Z-axis descends to EM and further to EB. Finally, the arm retracts to the RB position, when the motion of the command is finished.

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Conventional cylindrical coordinate type
(Cluster formation)

SCARA arm type
(Square formation)

In the field of semiconductor processing, there is a trend toward expanding the clean room area because more process equipment is required due to die shrink and multilayering. In order to solve this problem, we propose to shift vacuum transfer equipment from cluster formation to square formation.
Currently, a cylindrical coordinate type robot is used in cluster formation that makes movements of the robot arm easy to understand, but the footprint of the vacuum equipment becomes larger due to circular transfer module. By changing cluster formation to square formation and using a SCARA arm type robot to transfer wafers, the footprint of the vacuum equipment can be reduced.

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Realizes shorter delivery times by reduced wiring type wafer transfer robot

A reduced wiring type wafer transfer robot is a robot in which each component of the robot is modularized by superimposing various signals on the control power supply using high-speed power line communication.
Realization of the shortest delivery time of 45 days by assembling each module into a finished robot.

■ Specification checklist
(For the UT-AFX/W3000NM Series)

See specification checklist

■ Each module

The specification checklist includes each module. By selecting and ordering each module, a robot according to your needs can be created.
In addition to modules in the specification checklist, we offer various modules that can be selected from among 16 types for even a single robot body. “Arms,” “hands,” “hand bases,” etc., can also be selected. *Inquiry required

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Realizes energy-savings by sharing servo driver power supply.

We replaced a single-axis servo driver (former controller) with a multi-axis servo driver (new controller) for our long-selling machines. With this new servo driver, the regenerative energy generated during deceleration motion can be consumed on other axes, which was dissipated as heat by the regenerative resistor previously, and primary power consumption is suppressed, realizing energy-savings.