Equipment Constants

 

SEMI E30 Sections:	4.5
Database Usage:
Documentation Requirements:	You must document any Equipment Constant IDs that you create.

Equipment constants provide a way to store values for equipment parameters. These values control various aspects of equipment behavior (i.e., how many widgets to build, what parts to use for a widget assembly, etc.). Equipment constants are stored in the GEM Variables database (The GEM Variables Database).

This capability is implemented as specified in the SEMI standards. It is largely transparent to the local operator and equipment. The only requirement is that the operator define the equipment constants for any required constants that are not already defined in the GEM Variables database.

Built-in equipment constants are summarized in Predefined Collection Events and are referenced throughout this manual. User-defined ECs can be added to the GEM Variables database.

GEM Requirements

These GEM requirements are specified in Section 4.5.4 of SEMI E30:

1. Equipment constants (ECs) are stored in AIM databases on magnetic media.

2. The equipment constant is a constant when viewed from the equipment when the control state is ON-LINE/REMOTE.

• The host can change the EC anytime except for Process Related restrictions (see the table below).
• The equipment cannot change the EC when the control state is ON-LINE/REMOTE
• The equipment can change the EC when the control state is OFF-LINE

The host shall have the following capabilities and restrictions when the LOCAL state is active:

• During processing, the host shall be prohibited from modifying any equipment constants that affect that process. Other equipment constants shall be changeable during processing. The host shall be able to modify all available equipment constants when no processing is in progress.

CAUTION: It is the customer's responsibility to make sure that the equipment is in a "safe" condition before setting equipment constants. To help handle most cases the user can mark a variable as being "process related" or "not process related". The table below shows the relationship between the Control mode, the process state, and EC modification.

Control	Process Related Setting	Process State	Equipment Constant Modification
LOCAL	Process related	Running	No modification is allowed from the equipment or by the host.
REMOTE	Process related	Running	May be operator modified depending on the setting of the REMOTE mode configuration category. This is set in the GEM Variables database. Modification by the host is allowed.
LOCAL	Process related	Not running	Modification is allowed from the equipment and by the host.
REMOTE	Process related	Not running	Modification by the operator depends on the REMOTE mode configuration category setting for non-process related variables. Modification by the host is allowed.

3. The equipment must provide a collection event to alert the host whenever an equipment constant is changed by the operator. (See the built-in collection events listed in Predefined Collection Events. The collection event name is "Operator Equipment Constant Change". The number is 9200.)