Communications: electrical – Condition responsive indicating system – With particular system function
Reexamination Certificate
2001-02-14
2003-09-16
Mullen, Thomas (Department: 2632)
Communications: electrical
Condition responsive indicating system
With particular system function
C340S691600, C700S095000, C700S110000
Reexamination Certificate
active
06621412
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to fabrication systems, and, more particularly, to semiconductor wafer fabrication systems including one or more processing tools through which semiconductor wafers are processed in order to form integrated circuits thereon, wherein when a problem is detected with a processing tool a troubleshooting procedure is initiated to solve the problem.
2. Description of the Related Art
Integrated circuits are typically formed by processing one or more semiconductor wafers as a “lot” through a series of wafer fabrication tools (i.e., “processing tools”). Each processing tool typically performs a single wafer fabrication operation upon the semiconductor wafers of a given lot. For example, a particular processing tool may perform a layering operation, a patterning operation, a doping operation, or a heat treatment upon the semiconductor wafers. A layering operation typically adds a layer of a desired material to an exposed surface of the semiconductor wafers. A patterning operation typically contributes to the removal of selected portions of one or more layers formed by layering. A doping operation typically places dopant atoms upon and within exposed surfaces of the semiconductor wafers, thereby producing p-n junctions required for semiconductor operation. A heat treatment typically heats the semiconductor wafers to achieve specific results (e.g., dopant drive-in or annealing).
Each processing tool typically performs a wafer fabrication operation according to a predefined procedure (i.e., a predetermined set of steps or “recipe”). For example, a given chemical vapor deposition (CVD) processing tool may carry out a layering operation within a chamber according to a recipe which specifies temperatures and pressures within the chamber as a function of time, as well as the types and flow rates of gases introduced into the chamber.
Characteristics of processed wafers, such as characteristics of key integrated circuit structures formed during wafer fabrication, are typically measured to ensure the characteristics remain within acceptable ranges. In order to detect manufacturing problems as quickly as possible, such measurements are typically performed as soon as possible following critical processing steps. For example, special test structures may be formed on “test” wafers processed along with “product” wafers, or within test areas of the product wafers, and the characteristics of the special test structures may be measured. One common technique for tracking and analyzing manufacturing process variation is called statistical process control (SPC). SPC is typically used to gauge the stability of a manufacturing process over time via charted SPC data (i.e., SPC control charts) which document historical process performance.
When SPC data regarding one or more wafers processed through a given tool indicates a characteristic of the wafers affected by the processing tool has departed from an acceptable range established for the characteristic, an alarm condition may be signaled, and the processing tool may be shut down. In such a situation, a troubleshooting procedure is initiated, the object of which is to clear the alarm condition (i.e., solve the problem) and to return the processing tool to service as quickly as possible.
FIG. 1
is a diagram depicting a typical troubleshooting procedure initiated when a problem with a processing tool is detected (i.e., when a processing tool is subject to an alarm condition). The processing tool may be, for example, a furnace, and the alarm condition may be caused by the fact that a total number of particulate contaminants upon surfaces of wafers processed through the furnace exceeds an SPC upper control limit established for the furnace. When the problem is detected, the processing tool may be shut down due to the alarm condition. Alarm data
100
is presented to a user
102
(e.g., an operator or engineer). In
FIG. 1
, alarm data
100
is an SPC chart showing that that the total number of particulate contaminants upon surfaces of wafers processed through the furnace exceeds the SPC upper control limit.
Alarm data
100
defines the alarm condition (i.e., the problem with the processing tool). In response to alarm data
100
, user
102
may elect to employ a troubleshooting guide (TSG). A TSG represents a systematic method for clearing the alarm condition (i.e., solving the problem) and returning the processing tool to service.
Two of several known types of troubleshooting guides (TSGs) are shown in
FIG. 1. A
first type of TSG
104
is a textual document divided into sections. Each section may be, for example, directed to a different type or “class” of problem (i.e., “fault class” or “problem class”). Each problem class may be directed to a particular type of processing tool and/or a particular application of the particular type of processing tool. Each section of TSG
104
may be divided into subsections, and each subsection may include words describing one or more symptoms of the problem class. A given subsection may also include a probable cause and a corrective action for one or more of the described symptoms, wherein a corrective action is an action which must be accomplished to solve the problem (i.e., to clear the alarm condition). Where the given subsection does not include a probable cause and a corrective action for a described symptom, the described symptom is typically covered in another subsection, and the given section typically directs user
102
to the other subsection.
When employing textual document TSG
104
, user
102
must select a section dealing with the problem class indicated by alarm data
100
, then read through the subsections of the selected section until a symptom which matches the alarm condition is found. User
102
must then continue to read through the subsections as directed until a probable cause and corrective action corresponding to the symptom are found, then accomplish the corrective action.
A second type of TSG
106
is a flow diagram or flow chart having a single entry or “start” point and multiple steps along multiple paths between the start point and one or more end points. Each end point includes a probable cause for a symptom and a corresponding corrective action which must be accomplished to solve the problem. A path from the start point to a given one of the end points may correspond to a particular symptom. Decision steps of the flow chart are used switch a flow of troubleshooting activity from one path to another. When employing flow chart TSG
106
, user
102
must establish a path from the start point to one of the end points, accomplish all required actions along the path, then accomplish the corrective action stated in the end point.
Another known type of TSG is a table having multiple entries. Each entry of the table may include, for example, words describing a symptom, a probable cause for the symptom, and a corrective action which must be accomplished to solve the problem (i.e., clear the alarm condition). Such a tabular TSG may be divided into sections, and each section may be directed to a different problem class as described above. When employing such a tabular TSG, user
102
must select a section of the tabular TSG dealing with the problem class indicated by alarm data
100
, read through the symptoms of the table entries until a symptom which matches the alarm condition is found, then take the corrective action associated with the symptom.
It is noted that with all the known types of TSGs described above, the amount of time required to locate a corrective action corresponding to a symptom (i.e., a problem) generally depends on the problem class indicated by alarm data
100
and the length and construction of the TSG.
Alternately, user
102
may elect to use an ad hoc approach
108
to solve the problem as indicated in FIG.
1
. For example, faced with the particulate contaminant problem described above, user
102
may elect to clean (or direct the cleaning of) interior surfaces of the furnace in an effort to
Markle Richard J.
Weaver Elizabeth
Advanced Micro Devices , Inc.
Mullen Thomas
Williams Morgan & Amerson
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