Using a Web intranet for fab data distribution
07/01/1998
Using a Web Intranet for fab data distribution
Zbigniew Helak, Andrzej Buczkowski, Mitsubishi Silicon America, Salem, Oregon
Practically applied Web technology on an intranet has proven to be feasible and advantageous in a semiconductor materials production environment. The system provides data and information management, including data acquisition, processing, distribution, and work tracking. This model application includes classic data distribution via static Web pages, and dynamic interactive information exchange in real time between metrology instruments and a database via the Web server. As such, Web technology offers many advantages, including low installation and maintenance costs, and easy integration of text, graphics, and binary data formats. Further, the system provides flexibility because it is not dependent on a given workstation platform or network.
As the Technology Center at Mitsubishi Silicon America (MSA) developed, we knew we needed an advanced, yet cost-effective network for information flow. Specifically, we wanted a network that was:
capable of working in a heterogeneous environment, independent of network and workstation computer configurations;
effective in its distribution of information, including documents and databases;
capable of eventually meeting company-wide communications needs, including expansion into several departments and worldwide locations;
cost efficient for client-computer installations and maintenance; and
easily implemented, administered, maintained, expanded, and adapted to company organizational changes.
The traditional approach for reliable electronic access to manufacturing production data and standards uses a client-server database configuration (Fig. 1), where a part of each application resides on the client workstation and part on a server computer. With these systems, maintenance of corporate-wide client workstations can be costly and time consuming just to keep up with rapidly increasing applications. Moreover, the client software installation process is difficult, because many applications have contradictory requirements for disk-drive access, systems drivers, memory assignment, and user protocols.
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Figure 1. A traditional client-server database configuration.
Emerging, but still immature, alternatives that reduce the complexity of corporate computing associated with client-server installations include network computers, zero administration operating systems, and intranets. After studying the pros and cons of each approach, we chose to implement an intranet because of its market availability and its relatively advanced development compared to the other options.
There is a distinction between "intranet" and "the Internet." The latter is a global network of server computers, publicly and privately supported by many organizations, accessible by anyone with a properly configured computer. An intranet is a logical structure of servers and clients linked in a private network. An intranet is either totally isolated from the Internet, or information flow between the two is precisely controlled by "firewall" devices. The important connection is that an intranet applies Internet Worldwide Web ("Web") technology, specifically its hypertext markup language (HTML) programming for document preparation and its hypertext transfer protocol (HTTP) for the client-to-server link, in a controlled company-network; information distributed within a company`s intranet is not visible from the Internet.
First, static pages
We began by installing a Novell Web server that allowed HTTP requests and HTML distribution of static documents, HTML documents created manually from our databases of information (Fig. 2). Specifically, these pages contained information about our Technology Center`s analytical and processing capabilities, analytical instrumentation, equipment capacity, cycle-time analysis, and personnel.
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Figure 2. Web-server-based intranet configuration for static HTML-document retrieval; HTTP supports access to documents written in HTML and information posted in databases.
A Novell software and file server was the natural choice for the Web server, since MSA uses a Novell Netware network. Our Web server integrated with the existing network and Novell Directory Services allowed granular delegation of Web administration rights; access rights could be selectively assigned to MSA employees in charge of development of static information pages published on the intranet.
Our choice of the Novell Web server also enabled cost savings through Web and file server hardware integration: the Web server is simply an extra NetWare Loadable Module on the Technology Center`s server computer. Despite the large volume of data maintained on this computer, the average processor use was relatively low, so we were still able to dedicate it to Technology Center operations and have room for our developing Web applications.
Virtual pages
While our implementation of fast, reliable, static document distribution was an important step, we knew we needed the power of integrating databases with the Web server so data could be extracted on demand and HTML documents created and sent to a user on the fly as virtual pages (Fig. 3). We evaluated several commercial software packages that would allow us to do this before selecting Oracle database and Web server. This package offered the tightest integration of database and Web systems, and good applications development flexibility and scalability. Structured query language (SQL) functions running within the database create HTML pages, so anything that can be done by SQL can be triggered by a Web request. In addition, because the database and Web server were developed by the same software supplier, we saw that this system offered the highest transaction speed and effectiveness of all solutions evaluated.
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Figure 3. The real power of an intranet is achieved when it provides on-the-fly HTTP and HTML access to company databases.
The Technology Center uses total x-ray fluorescence (TXRF) to evaluate MSA`s wafer-manufacturing process for surface metal contamination. The TXRF instrument measures the wafer and stores its raw data on the Technology Center`s file server. Then, independent of the Web server, the TXRF operator selects and uploads the appropriate data to the intranet. The intranet is used only for querying the database; no database update originates from the intranet.
With the TXRF data now integrated on the Web server, users at workstations equipped with Internet browsers could dynamically queue the database (Fig. 4) to obtain virtual Web pages sorted by manufacturing process, analytical technique, time, average and extreme values in a period, etc. (see Figs. 5a and b for examples). (The data in Figs. 5a and b, and subsequent illustrations, are generic to protect MSA proprietary information.) Little human involvement is required in the production of virtual pages; specifically, only a data upload is necessary after a batch of wafers is processed through TXRF.
Compared to our previous manually prepared static pages, the advantage of virtual-page generation is obvious, considering the dozens of process-monitoring techniques used at MSA; several hundred static pages would be required if the process-monitoring data were not available on the intranet. Clearly, introduction of virtual pages resolved the problem of time and human involvement in static page creation.
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Figure 4. With data loaded into databases on the Web server, an Internet browser enables information retrieval across the company intranet.
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Figure 5. a) Data access screen created on the fly from intranet access to the TXRF database based on data extracted from the database. A user can click on the colored bullets to develop specific queries and b) more detailed reports.
Applying "cookies"
Our next step addressed the modification of databases via the intranet interface. Initially, we noted Web technology`s inherent lack of ability to keep track of a user`s session; every HTTP request sent to any Web server creates a separate session that is automatically closed when requested data is returned. So, HTTP protocol by itself does not provide the means for passing variables from one screen to the other and does not even maintain user identity while browsing several screens. We recognized this as a serious limitation if access to certain data was to be restricted to authorized individuals. It would also be limiting when a user had to perform a transaction through a sequence of screens and data entry.
Our solution was the application of "cookie passing." As users of the Internet`s Worldwide Web know, a "cookie" is a block of data that a Web server stores on a client system. When a user returns to a Web site, the browser sends a copy of the cookie back to the server. Cookies are used to identify users, to instruct the server to send a customized version of the requested Web page, to submit account information for the user, or for other administrative purposes.
We developed a software module with our Oracle package that enabled user identification and session tracking. To gain access to secured portions of our intranet, a user logs on with a password, then every user`s step through the intranet is tracked.
The user`s browser receives a cookie that is valid for only one request to the Technology Center`s Web server. It acts as a key that changes after every page is retrieved, not only for security reasons, but also to prevent the user from hitting the back icon several times while in the middle of a transaction that has already been processed. If this should happen, the software module warns that processing has been discontinued, and the user must start further data entry from a defined point. The module also enables collection of user statistics and access history.
Workload tracking
Overcoming user-identification, session-tracking problems also allowed us to expand data management into the Technology Center`s workload tracking application; this was originally written in Visual FoxPro and was only accessible by Technology Center personnel. It tracks every order for material analysis placed with the Technology Center, including the customer, requester, log-in date and time, and work description.
Transferring this information to our intranet improved Technology Center workload visibility and provided instant information to our customers about the stage of requested processing. The new user interface for this application is entirely designed for intranet use. All database modifications originate from the Web, and Technology Center personnel have the ability to enter data into the system from any corporate computer with an intranet browser. Any changes in the database are instantly reflected in the pages returned to Technology Center customers.
In use, the workload-tracking system creates an HTML link to a final version of an analysis report as soon as it becomes available; the report is produced in Microsoft Word format that Technology Center customers can immediately download. Users can search the workload-tracking database by customer, requester, analysis instrumentation, and problem description. A search produces a list of references to orders in progress or to work reports if the analysis was complete.
Today, we are expanding the system to include tracking of the materials flow through the Technology Center. Each individual box with samples coming to the Technology Center is bar-coded, and the system records the box`s history at every stage of processing. In addition, another intranet-based software module provides a database on materials in storage. This module allows for location of every sample container at every stage of processing, including storage.
Real-time database updates
With controlled interactive and secure data exchange from the Oracle database via Internet browsers across our intranet, we were able to expand our system to include real-time database updates from metrology instrumentation. One such example is gas fusion analysis, where the metrology instrument is permanently connected to the database and uploads data in real time while the metrology process is done. This setup uses an additional computer as an interface between the instrument and the database (Fig. 6); the computer converts the output from the metrology instrument received via a communication port, extracts the needed data, checks it against business rules, and outputs the result into the database. As soon as associated metrology data is in the database, it can be accessed via a Web page.
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Figure 6. Metrology instruments feed their data to the intranet database via an interface-data-normalization computer. Information is fed into the database in real time, providing updates to the Web page as metrology progresses.
The net result is a much faster data delivery process, elimination of human errors in information transfer, and remote work progress monitoring. The Web pages can actually change content in real time. When needed, the system can generate a report and data summary based on measurement progress. Report generation is achieved using an intranet-based application that calculates necessary fitting coefficients based on daily calibration data. This application is designed as an Oracle module that an instrument operator or the area supervisor can execute via Web interface. With the previously described session-tracking capability, reports can be created, accessed, and edited from any computer within MSA via intranet access after positive user identification.
Automatic reports
Finally, we introduced a separate computer that automated data reporting (Fig. 7). Here, the Technology Center Web site provides standard reports and charts that are updated daily. The computer wakes up automatically at the appropriate time, connects to the database, and generates the required reports according to established specs.
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Figure 7. A background-data-processing computer automatically generates and publishes standard periodic summary reports on the intranet.
This process creates static charts as GIF (graphics interchange format) files, pure HTML code, and Microsoft Word and Excel documents. The process relies on object linking and embedding automation when generating Word and Excel documents. Automatic report generation also sends e-mail messages using messaging application programming interface (MAPI), if data shows any of a number of programmed deviations. These are sent to appropriate MSA employees for action.
Fast implementation
It is worth noting that Web technology development can be very fast and practical company-wide. Consider, in a simple example, the fact that we created a company-wide electronic telephone book connected to a database owned by the MSA Human Resources Department in just a few days. This application allows searching for a person by combinations of first, last, or maiden names, or even by nickname or department. The screen always returns the employee`s official first and last names.
Conclusion
A company-wide intranet configured with Web technology is a very promising, flexible, and cost-effective computer technology for semiconductor manufacturers. When integrated with databases, it allows for instant sharing of information independent of computer platform and with much lower maintenance costs compared to the traditional, direct workstation-database combination. It enables integration of information systems separated geographically by great distances. When Web technology is implemented, it can increase work efficiency through better information distribution, reduction of interdepartmental miscommunication, and better interdepartmental and human integration.
Acknowledgment
NetWare, Novell Directory Services, and NetWare Loadable Module are registered trademarks of Novell Inc. Microsoft Word, Microsoft Excel, and MAPI are registered trademarks of Microsoft Corp.
ZBIGNIEW HELAK received MS degrees in electronics and computer science from Technical University of Wroclaw, Poland, in 1985 and 1988. From 1985 to 1994, he developed hardware and software for microprocessor-based, embedded measurement and control systems for semiconductor research applications at Technical University. From 1994 to 1995, he was a visiting professor at North Carolina State University, Raleigh, NC, working on silicon properties characterization. Since 1995, he has been network, database, and Web designer and administrator at the Technology Center of MSA. 1351 Tandem Ave. NE, Bldg. #7, Salem, OR, 97303; ph 503/361-3456, fax 503/315-6103, e-mail [email protected].
ANDRZEJ BUCZKOWSKI received his PhD degree in electronics from Technical University of Wroclaw, Poland, in 1978. From 1978 to 1989, he worked in research, development, and characterization of silicon and gallium arsenide materials and devices at Technical University. He continued this research at North Carolina State University, Raleigh, NC, as a visiting research professor. Since 1993, he has been leading silicon materials and evaluation technology development in the area of electrical properties at MSA. He also supervises information flow and data management in MSA`s Technology Center.