300mm Semiconductor Review Station

Also:
Image Acquisition and Archiving
Semiconductor Factory Automation
High Speed Turbine Controller

Technologies, Tools and Standards Employed:
Visual Studio C++, Win32 SDK, MFC, NT Driver SDK, ActiveX, COM, ATL, Visual Basic, TCP/IP, WINSOCK, VxWorks, Tornado, Motorola 68000 embedded, x86 embedded, VME bus interface, Semiconductor Equipment Manufacturers International (SEMI) standards E4, E5, E30 (GEM), E37

Problem:
Design a 300mm wafer defect review software package which will coordinate the activities of a high speed scanning electron microscope (SEM) wafer defect review station.  This station is intended for in-line use in 300mm wafer fabrication facilities.  The software will read an input list of wafer coordinates, load and align wafers, locate, image, and classify each defect. This software must coordinate the activities of all SEM subsystems as well as collect and distribute defect data, analyze and store images, and provide factory communications interfaces (SEMI GEM capability). The system will use a Windows PC for top level control and a VME chassis system to provide lower level functionality. Several already-existing 8 and 16-bit embedded processor boards (designed by Acorn) will be integrated into the project.

Solution:
Our design and implementation of a defect review system for inspecting semiconductor in-process wafers was the first of its kind and continues as the top-level entry from our client.  The system optimizes and overlaps stage seek and image analysis/archive operations to minimize move, acquire, measure (MAM) times. The following software subsystems were designed and implemented by Acorn to solve this problem.

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Automated Defect Review Application

A fully automated defect review application based on a scanning electron microscope (SEM) platform. This flagship product coordinates the actions of several subsystems to:

 

  • Provide a comprehensive yet simple and easy to learn graphical user interface for job setup, control and status monitoring
  • Find and image a sampling of semiconductor wafer defects
  • Annotate and archive images of each defect
  • Provide for automatic x-ray and defect classification
  • Arrange the defects into classification categories
  • Output results to a factory host
  • Respond to factory automation commands (SEMI E-30 standard, GEM)

The defect review program is a highly streamlined, multithreading application which overlaps operations and minimizes the defect-to-defect processing time - the bottom line requirement for semiconductor fabrication lines.

5-Axis Stage Motion Controller

A 5-axis stage motion control package used to accurately position semiconductor wafers to within .5 microns. The software implements the coordinate transformations necessary to calibrate each individual stage and to remove orthogonal, linear and non-linear motion errors..  The package has been optimized for 300mm wafers and supports stage error mapping, n-point coordinate warping and optical alignment.

Robotics Controller

A wafer transfer controller used to coordinate vacuum and atmospheric robots for wafer loading, vacuum management and interlocks and wafer alignment activities.

Image Capture Package

An image capture and transfer package based on a proprietary video capture board and an off-the-shelf VME bus emulator. The problem solved was to transfer SEM images from a VME based frame buffer to a Windows based PC in the shortest amount of time possible. High speed is essential because there are only seconds to process and identify each defect.

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Electron Beam Scan Controller

A scanning and acquisition control package to handle beam alignment and calibration, scanning rate and video frame averaging, and to coordinate the action of several VME based subsystems used to control video gain, focus and scanning.

Embedded Motorola CPU

A VME based, embedded Motorola CPU, programmed with a suite of software modules to control and coordinate the various low-level SEM operations. This board stands between the Windows PC and the SEM low level hardware. It is responsible for robot motion, vacuum control, coordination of image scanning and acquisition, PC communications via VME bus emulation.

Windows Drivers

Kernel drivers necessary to implement the PC to VME link via high-speed VME bus emulator communications interface.

SEMI GEM Standards

SEMI (Semiconductor Equipment Manufacturers International) standard GEM (E-30) interface to provide status, upload/download recipes and to receive factory host remote commands. An automatic light tower was added later.

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