JST Goes to Great Lengths to Advance Semiconductor Manufacturing with Rexroth Automation

挑战
Create a 138-foot-long wet bench silicon cleaning station utilizing multiple Cartesian robots driven by a combination of linear motion and control technologies

Rexroth Solution

• CKR belt-driven linear modules
• CKK ball screw linear modules
• MKR belt-driven linear modules
• IndraDyn MSK synchronous servo motors
• IndraDrive C digital intelligent servo drives
• Rexroth EasyHandling System

结果

• Effective use of overhead Cartesian robots
• 清洁站的138英尺长度的精度，准确性和可重复性
• 稳健性和可靠性
• Cleanliness to Class 10 cleanroom standards
• 系统订购为单零件号

Background
Although silicon is the key ingredient for semiconductors used in smartphones and other electronic devices, only a purified form can be used to make semiconductor chips. Producing semiconductor- grade silicon involves upstream processing of polysilicon chunks to a purity of “11N,” which translates to 99.999999999 percent. That’s a challenge that JST Manufacturing (Boise, ID www.jstmfg.com) helps customers meet by building advanced wet bench cleaning stations using linear motion and electric drive and control technology from Bosch Rexroth Corporation (Charlotte, NC www.boschrexroth-us.com).

JST builds cleaning and processing equipment for cleanroom applications, from single wafer etching to automated wet process equipment. “That includes wet bench cleaning stations of all sizes, but typically no more than 30 feet long,” says Tony Bertagnolli, chief operations officer. “But recently for an overseas customer, we built a 138-foot-long line that employs multiple gantry robots. Handling the robot travel requirements for that distance took a combination of linear motion and control technologies with the precision, robustness and cleanliness that only Bosch Rexroth could provide.”

保持纯度清洁多硅块
JST的湿台清洁站部署在硅制造工艺开始时。在那个阶段，长圆柱多硅胶杆（称为锭）被分成大约一到三英寸的大块 - 不比拳头大。将块放入特殊的篮子中，这些篮子进入一个车站的化学蚀刻罐，以去除硅氧化物和其他污染物。然后，块被浸泡，冲洗和干燥。在一个单独的过程中，将块融化在炉子中，并变成纯净的单晶硅缸，这些硅缸被冷却，蚀刻并最终发展为计算机芯片。

For the front-end chunk cleaning process, JST’s wet bench station was designed to process approximately four tons of silicon chunks in a 22-hour shift. To maintain that throughput, one basket holding 44 pounds of silicon chunks has to be cleaned every 6.6 minutes.

“That requires a unique wet bench cleaning station design,” says Bertagnolli. “We engineered and built a station comprised of two units— the A1 and A2.” In the 24-foot-long A2 unit, baskets of chunks are manually loaded through an auto-door. Then two-axis robots cycle the baskets through five acid etch baths and two rinse baths arranged in a single row down the length of the X-axis. As the baskets move down the X-axis, they are lowered into each chemical and rinse bath (Z-axis).

After completing the acid etch and rinse steps in the A2 unit, the baskets are transferred automatically through an airlock into the 88-foot-long A1 section of the line, which uses three-axis gantry robots to cycle the baskets through two X-axis rows containing soak and dry baths. At the end of the process, the empty baskets are automatically unloaded using customer-supplied conveyor belts.

“What’s unusual is that the A1 unit employs overhead gantry, or Cartesian robots. Overhead Cartesian robots are not often used in semiconductor process systems to avoid generating particles overtop the product. However, after extensive particle testing in cleanroom conditions, we found that the Rexroth profiled linear guide rails and linear motion modules used in the system generated far fewer particles than the specifications allowed. It’s a real credit that the Rexroth Cartesian motion components can handle that level of cleanliness,”

在整个过程中，保护组件免受污染和点蚀至关重要。Bertagnolli强调：“ Rexroth密封使线性运动滚带保持清洁。”“并且它们防止化学蚀刻蚀刻线性模块。”Bosch Rexroth合并了其他功能，以确保系统达到10级洁净室标准或更好的标准。运动系统组件使用薄薄的致密镀铬镀层来耐腐蚀。他们还用洁净室的油脂润滑。

Unique linear motion system goes the distance handling heavy silicon chunks
In addition to using an overhead gantry design, the station’s length also posed unique challenges. According to Bertagnolli, JST usually builds semiconductor cleaning stations in 12- to 30-foot lengths.

To handle the A1 length of 88 feet, each side of the X-axis on which the gantry robots travel is assembled from six, 10-foot sections and three, 9-foot sections of Rexroth profiled linear guide rails mounted on high- strength Rexroth extruded aluminum structural framing. Due to the length, the framing and profiled rails needed to fit precisely at the joints to ensure smooth motion of the robots.

每个龙门机器人的马车都使用Bell-Everman，Inc。（Goleta，CAwww.bell-everman。com）的双同步Servobelt™线性运动模块沿X轴向下驱动，并在龙门的每一侧都有一个模块。与常规的单带驱动器不同，每个Servobelt模块都由一对齿的钢筋T5聚氨酯带和Bosch Rexroth Indradyn MSK同步伺服电机提供动力。伺服电动机在模块上骑在剖面的轨道上时，它与模块一起行驶，它转动了一条上层“活跃”皮带，该皮带与较低的，永久性粘合的“静态”皮带接头（见图1）。皮带驱动的设计大大增强了这一漫长跨度的刚度，准确性和可重复性，该设计提供了许多与电动线性电动机相同的好处，但具有与常规线性模块相当的值。

为了确保准确性和重复性,力士乐IndraDrive C digital intelligent servo drives synchronize the motion of the ServoBelt modules via a master-slave configuration. “We get smooth and precise travel over the long X-axis length,” said Bertagnolli. “The synchronization between the two modules is very accurate.” As the chunks move through the wet bench cleaning station, control and timing sequences are performed by a third-party PLC control platform.

To move the baskets laterally from one bath to the other as the robot carriages travel down the rails, the gantries incorporate other Rexroth linear motion technology. For the Y-axis, each gantry uses a Rexroth CKR belt-driven linear module powered by another Rexroth IndraDyn MSK servo motor. The CKR module has a 48-inch stroke as the baskets travel over two rows of soak and dry tanks.

To raise and lower the baskets with the polysilicon chunks into the soak and dry baths, the gantry robots on the A1 unit utilize Rexroth CKK ball screw linear modules. These provide the vertical Z-axis movement with a 32-inch stroke to lower and raise the assembly that dips the baskets into each bath. Each arm terminates in a J-hook end-effector that fits a pair of slots in each basket.

“球螺钉必须承受一定量的扭矩。与其他供应商的球螺钉相比，Rexroth线性执行器被证明更可靠和健壮。从浴缸中抬起篮子时，Z轴的加速度平稳而迅速。” Bertagnolli说。

The A2 unit uses the same type of dual ServoBelt linear modules to move the gantry carriage assemblies down the X-axis, traveling approximately 20 feet. Unlike the A1 unit, no lateral Y-axis motion is required because there is only a single row of baths. To raise and lower the baskets into the etch and rinse baths, the Z-axis motion is provided by another set of Rexroth CKK ball screw actuators.

Seed rod processing uses more linear motion
In a separate application for the same customer, JST also created a standalone system to clean the seed rods that grow the polysilicon ingots from which chunks are made.

处理远距离的机器人旅行要求将线性运动和控制技术结合在一起，其精确性，稳健性和清洁度只有仅Bosch Rexroth才能提供。

The seed rods are mounted in specially designed cylindrical carriages which revolve inside each etch bath. As with the A1 and A2 systems, the seed rod cleaning tool also utilizes a gantry robot to move the ingot-carrying cylindrical carriages through a sequence of etch baths.

For this tool, two Rexroth MKR linear modules mounted on either side of the row of baths are used to move the cylindrical carriage down the X-axis from start to finish. Each MKR linear module consists of a 23.5-foot-long ball rail and toothed belt drive powered by a Rexroth IndraDyn MSK servo motor with multi-turn absolute feedback.

To raise and lower the cylindrical carriages into each bath, a Rexroth CKK module with a side-mount servo motor was utilized, while a rotary end- effector on the carriage carousel spins the rods in the tanks.

For these and other projects, JST works with automation partner Northwest Motion, Inc. (Issaquah, WA www.nwmotion.com), a distributor of Rexroth drive and control products. In this case, the electric drives, rails and linear modules for the three units were provided via single Rexroth EasyHandling System part numbers to ensure all components worked together as an integrated gantry robot solution.

Bertagnolli指出：“我们非常感谢如何将每个电台的Rexroth组件都订购为单个零件号。”“我们必须在设计批准后的十个星期开始建造，因此这有助于我们满足生产计划。多年来，Rexroth Drive和Control产品为我们带来了竞争优势。在将这一部分结合在一起时，必须精确地消除导轨和剪接套件的拟合和形式。在此应用程序中，Rexroth笛卡尔运动系统表明，我们竭尽全力满足客户的确切规格。”

Servobelt™是Bell-Everman，Inc。的商标。

©2014 Bosch Rexroth Corporation

Subject to change without notice

ALL RIGHTS RESERVED

FORM bos-2893-12-2014