Radiant energy – Inspection of solids or liquids by charged particles – Electron probe type
Reexamination Certificate
2000-08-17
2003-12-02
Lee, John R. (Department: 2881)
Radiant energy
Inspection of solids or liquids by charged particles
Electron probe type
C250S307000, C250S492300, C324S754120, C324S1540PB
Reexamination Certificate
active
06657192
ABSTRACT:
The present application claims priority under 35 U.S.C. 119 to Korean Application No. 99-33858 filed on Aug. 17, 1999, which is hereby incorporated by reference in its entirety for all purposes.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to the manufacture of semiconductor devices, and more particularly, to a method of determining the degree of charge-up induced by plasma according to a plasma process, a method for determining whether a contact hole is open using the same, a method for determining the degree of degradation of a gate insulating layer induced by plasma, and an apparatus therefor.
2. Description of the Related Art
A process of using plasma to etch a material layer is used in manufacturing semiconductor devices. For example, in a process of forming a contact hole which exposes a material layer under an insulating layer by etching the insulating layer, the insulating layer is patterned using plasma as an etching medium. At this time, charge separation may occur in an insulating layer pattern due to the electrical characteristic of the plasma. Ions accumulate inside the contact hole of the insulating layer pattern, that is, on the bottom of the contact hole due to charge separation. This so called charge-up can cause various defects in semiconductor devices. For example, when a contact hole exposing a gate electrode is formed, charge-up caused by the plasma process may degrade a gate insulating layer under the gate electrode.
For example,
FIG. 1
schematically shows the distribution of charges which are charged up when a contact hole
45
is formed by a plasma process. The degradation of a gate insulating layer
20
caused by the plasma process is described in detail as follows. During formation of contact hole
45
by a plasma process, charge separation may occur at the bottom and top of the contact hole
45
. That is, almost all ions of the plasma which are accelerated by a sheath travel in a straight direction, thus accumulating at the bottom of the contact hole
45
as ions
50
. Meanwhile, electrons of the plasma accumulate at the upper portion of the contact hole
45
as electrons
55
due to isotropic angular momentum distribution of electrons. This means that the (−) charges are charged up in the upper portion of the contact hole
45
and the (+) charges are charged up on the bottom portion of the contact hole
45
. Such a charge-up phenomenon can occur in a plasma etching process for forming a trench or a line and a space structure, as well as in a process of forming a contact hole such as contact hole
45
.
Ions
50
which are accumulated at the bottom of the contact hole
45
, the trench or line, or the space structure due to charge separation can have the effect that a positive voltage is applied on the gate electrode
30
. This positive voltage can affect the gate insulating layer
20
. Charge-up of the gate insulating layer
20
continues while the plasma process continues and charges which are charged up due to charge separation reside after the plasma process is terminated. Accordingly, the effect of applying the positive voltage to the gate insulating layer
20
is maintained. The gate insulating layer may be damaged by charge-up thereof, that is, the effect of continuously applying the positive voltage may degrade gate insulating layer
20
. Incidentally, when the plasma process is performed, the charge-up phenomenon caused by the plasma cannot be avoided. Also, it is not possible to prevent the material layer such as the gate insulating layer
20
from being degraded or damaged by the charge-up phenomenon.
Additionally, high integration of semiconductor devices due to a reduction in the design rule results in an increase in the aspect ratio of contact hole
45
, for example. Accordingly, the line width of the bottom of the contact hole
45
is reduced and the height of the insulating layer pattern
40
is relatively increased. This makes the degree of charge-up induced by the plasma to the insulating layer pattern
40
severe. Therefore, degradation of the gate insulating layer
20
due to charge-up induced by the plasma becomes severe.
It is thus necessary to measure the degree of charge-up due to a plasma process in order to minimize or prevent damage to or degradation of the gate insulating layer caused by the plasma. A plasma damage monitoring (PDM) method has recently been used for measuring the degree of charge-up induced by the plasma. In the PDM method, the degree of damage to the gate insulating layer caused by the plasma is measured based on a change in capacitance of a wafer including the gate insulating layer. However, since the PDM method has limitations with respect to spatial resolution and calibration, the PDM method is used for measuring the degree of charge-up with respect to a flat material layer. Therefore, the PDM method has limitations in connection with measuring the degree of charge-up with respect to a wafer on which patterns are formed.
SUMMARY OF THE INVENTION
The present invention is therefore directed to an apparatus and method for determining charge-up induced by plasma or the degree of charge-up with respect to a wafer on which patterns are formed, which substantially overcomes one or more of the problems due to the limitations and disadvantages of the related art.
It is therefore an object of the present invention to provide an apparatus for determining charge-up induced by plasma or the degree of charge-up with respect to a wafer on which patterns are formed.
It is another object of the present invention to provide a method of determining charge-up induced by plasma or the degree of charge-up with respect to a wafer on which patterns are formed.
It is another object of the present invention to provide a method for determining whether a contact hole is opened.
It is another object of the present invention to provide a method of determining the degree of degradation of a gate insulating layer caused by charge-up induced by a plasma process used to form an insulating layer pattern, the insulating layer pattern having a contact hole which exposes a gate electrode and wherein the gate insulating layer is formed under the gate electrode.
Accordingly, to achieve the first object, there is provided an apparatus for determining the degree of charge-up induced by plasma used for manufacturing a semiconductor device, comprising a wafer on which a plasma process is performed, an electron beam generator for generating a beam of primary electrons for repeatedly scanning a predetermined region of the wafer, a detector installed on the surface of the wafer to be separated from the wafer by a predetermined distance, the detector for collecting secondary electrons generated by the reaction between the primary electron beam and the surface of the wafer and emitted to the outside of the surface of the wafer, and a determination unit for determining the degree of charge-up induced to the surface of the wafer by plasma used for the plasma process from the change in the amount of secondary electrons collected by the detector.
To achieve the second object, in a method for determining the degree of charge-up induced by plasma used for manufacturing a semiconductor device, a wafer, on which a plasma process is performed, is introduced. Secondary electrons generated by a reaction between a primary electron beam and the surface of the wafer that are emitted to the outside of the surface of the wafer are collected by repeatedly scanning the primary electron beam on a predetermined region of the surface of the wafer. The degree of charge-up induced at the surface of the wafer by the plasma used for the plasma process is determined from the change in the amount of collected secondary electrons.
The step of determining the degree of charge-up can be performed as follows. Namely, a sample graph, which shows the change in the amount of collected secondary electrons with respect to the number of scans of primary electrons, is provided. A reference graph, which shows the change in the amount of
Kim Ji-soo
Park Wan-jae
Shin Kyoung-sub
Fernandez K.
Lee John R.
Volentine & Francos, PLLC
LandOfFree
Method of determining degree of charge-up induced by plasma... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of determining degree of charge-up induced by plasma..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of determining degree of charge-up induced by plasma... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3127636