Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2001-08-01
2004-04-27
Picard, Leo (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C216S059000, C700S045000
Reexamination Certificate
active
06728591
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to semiconductor manufacturing, and, more particularly, to a method and apparatus for performing process control adjustments based upon trench profiles.
2. Description of the Related Art
The technology explosion in the manufacturing industry has resulted in many new and innovative manufacturing processes. Today's manufacturing processes, particularly semiconductor manufacturing processes, call for a large number of important steps. These process steps are usually vital, and therefore, require a number of inputs that are generally fine-tuned to maintain proper manufacturing control.
The manufacture of semiconductor devices requires a number of discrete process steps to create a packaged semiconductor device from raw semiconductor material. The various processes, from the initial growth of the semiconductor material, the slicing of the semiconductor crystal into individual wafers, the fabrication stages (etching, doping, ion implanting, or the like), to the packaging and final testing of the completed device, are so different from one another and specialized that the processes may be performed in different manufacturing locations that contain different control schemes.
Generally, a set of processing steps is performed on a group of semiconductor wafers, sometimes referred to as a lot. For example, a process layer composed of a variety of materials may be formed above a wafer. Thereafter, a patterned layer of photoresist may be formed above the process layer using known photolithography techniques. Typically, an etch process is then performed on the process layer using the patterned layer of photoresist as a mask. This etching process results in formation of various features or objects in the process layer. Such features may be used for a gate electrode structure for transistors. Typically, shallow trench isolation (STI) structures formed on the semiconductor wafers are filled by forming silicon dioxide using tetraethoxysilane (TEOS), over the wafer and in the STI structures. The manufacturing tools within a semiconductor manufacturing facility typically communicate with a manufacturing framework or a network of processing modules. Each manufacturing tool is generally connected to an equipment interface. The equipment interface is connected to a machine interface to which a manufacturing network is connected, thereby facilitating communications between the manufacturing tool and the manufacturing framework. The machine interface can generally be part of an advanced process control (APC) system. The APC system initiates a control script, which can be a software program that automatically retrieves the data needed to execute a manufacturing process.
FIG. 1
illustrates a typical semiconductor wafer
105
. The wafer
105
typically includes a plurality of individual semiconductor die
103
arranged in a grid
150
. Photolithography steps are typically performed by a stepper on approximately one to four die locations at a time, depending on the specific photomask employed. Photolithography steps are generally performed to form patterned layers of photoresist above one or more process layers that are to be patterned. The patterned photoresist layer can be used as a mask during etching processes, wet or dry, performed on the underlying layer or layers of material, e.g., a layer of polysilicon, metal or insulating material, to transfer the desired pattern to the underlying layer. The patterned layer of photoresist is comprised of a plurality of features, e.g., line-type features, such as a polysilicon line, or opening-type features, that are to be replicated in an underlying process layer.
Turning now to
FIG. 2
, a silicon substrate
210
that contains a plurality of layers
220
,
230
, is shown. In one embodiment, a layer of silicon nitride is added on the surface
215
of the silicon substrate
210
, producing the layer
220
. Trenches
240
are formed that extend through layer
220
of silicon nitride and into the silicon substrate
210
. Any of a variety of etching processes may be employed to create the trench
240
. The trenches
240
in the silicon substrate
210
generally have a finite trench depth
250
. The trench depth
250
extends from the bottom of the trench
240
to a top surface of the semiconductor wafer. Generally, the silicon nitride layers
220
are removed in the finished product.
FIG. 2
also illustrates a pre-polished layer of silicon dioxide material deposited on the silicon substrate
210
, which is represented by layer
230
. Generally, TEOS, which is a source gas, is used in the deposition process. Ideally, the silicon dioxide completely fills the trench depth
250
.
Maintaining predetermined trench profile characteristics, such as trench depth
250
, is important in semiconductor wafer manufacturing. Trench characteristics can affect the performance of a device manufactured from a processed semiconductor wafer. For example, variations in STI structures formed on a semiconductor wafer can affect the electrical characteristics of the semiconductor wafer. This, in turn, can affect the quality of devices produced from the processed semiconductor wafers.
Controlling trench profile characteristics during semiconductor wafer processing is generally difficult. Many times, loss of control of processing of trench structures on layers of semiconductor wafers can cause excessive variations among trench structures on the semiconductor wafers
105
. These variations can cause undesirable electrical characteristics associated with the operation of devices manufactured from the semiconductor wafers.
Turning now to
FIG. 3
, trenches
240
formed in a process layer
210
is illustrated. During processing of trench structures, loss of control can result in a trench depth
250
that is larger or smaller than a predetermined target value, or a range of values. A trench
240
with incorrect trench depth
250
can result in defective semiconductor wafers
105
. Furthermore, loss of control of processing of trench structures can result in diminished ability to form trench structures that contain sidewalls
305
at the appropriate angles. The sidewall angle, &thgr;,
320
can be greater or smaller than a predetermined target value, or a range of values. Variations in the sidewall angle
320
can cause undesirable fluctuations in the electrical characteristics of structures associated with the trenches
240
, resulting in defective semiconductor wafers
105
.
Generally, when loss of control of processing of trench structures occurs, many actions may be taken. For example, the processing chamber, e.g., etch chamber, in which the trench structures are formed, may be shut down and cleaned in an effort to return the chamber to a known steady state condition. The control of processing of trench structures is then re-initiated. However, the shutting down of a process chamber is inefficient and delays manufacturing of semiconductor wafers. Furthermore, frequent cleaning of process chambers requires a manufacturing system to constantly re-establish control of processing of trench structures from an initial state, resulting in additional delays and expenses.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
SUMMARY OF THE INVENTION
In one aspect of the present invention, a method is provided for performing run-to-run control of trench profiles. At least one semiconductor wafer is processed. A trench metrology data from the processed semiconductor wafer is acquired. Data relating to at least one process chamber characteristic, the data acquired while processing the semiconductor wafer is acquired. A chamber characteristic adjustment process is performed in response to the trench metrology data and the data relating to the processing chamber characteristic. A feedback adjustment of the processing chamber characteristic is performed in response to the chamber characteristic adjustment process.
In another aspect of the pr
Hussey, Jr. James H.
Purdy Matthew A.
Picard Leo
Shechtman Sean
Williams Morgan & Amerson P.C.
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