Semiconductor device manufacturing: process – With measuring or testing
Reexamination Certificate
1999-06-08
2002-05-07
Nelms, David (Department: 2818)
Semiconductor device manufacturing: process
With measuring or testing
C438S401000
Reexamination Certificate
active
06383823
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an SPM probe, particularly a self-detecting SPM probe having a piezoresistor.
A scanning probe microscope (SPM) such as an atomic force microscope (AFM) is widely used to observe small region of nanometer order on a sample surface nowadays. The SPM uses an SPM probe which a tip is formed at edge thereof as a scanning probe. In the SPM using the probe, shape of the sample surface is measured by scanning the sample surface with the tip of the SPM probe, and by detecting interaction (attractive force or repulsive force) generating between the sample surface and the tip as bending quantity of the SPM probe.
Bending quantity of the SPM is detected by irradiating laser beam to the SPM probe and by measuring change of the reflected angle. Here, the SPM probe used for this system is called optical lever SPM probe. However, fine adjustment of irradiating angle of the laser beam irradiating to the SPM probe and position of a photodiode detecting the reflected beam from the SPM probe is need at use of the optical lever SPM probe. Particularly, there has been complicated that the fine adjustment should be repeated at exchange of SPM probe carried out frequently.
Then, a self-detecting SPM probe detecting bending quantity of the SPM probe by forming a piezoresistor at the SPM probe and by measuring change of the resistance value is drawing public attention.
Constitution of the conventional self-detecting SPM probe is shown in FIG.
13
and FIG.
14
.
FIG. 13
is a plane view and
FIG. 14
is a sectional view taken along line D-D′ of FIG.
13
. As shown in
FIG. 13
, a self detecting SPM probe
100
comprises an SPM probe
102
having a tip (not shown) at edge thereof and a reference
104
for measuring reference resistor value. These SPM probe
102
and reference
104
form U-shaped piezoresistors
108
and
110
each on surface thereof. Here, the piezoresistors
108
and
110
are formed on an n-type silicon substrate
106
as injecting selectively p-type impurity ion in U-shape each as p
+
piezoresistor.
Moreover, as shown in
FIG. 14
, silicon oxide film (SiO
2
)
112
protecting the surface except a metal contacting portion of the SPM probe and a metal contacting portion of the reference
104
is formed. Aluminum electrodes
114
,
116
,
118
, and
120
for contacting are produced at each of metal contacting portions. Although p
+
piezoresistors
108
and
110
are formed at surface of n-type silicon substrate
106
by injecting p-type impurity ion, reversely at use of p-type silicon substrate, n
+
piezoresistors are formed by injecting n-type impurity ion.
Observation of the sample surface by the above conventional self-detecting SPM probe
100
is carried out by scanning the sample surface with the SPM probe
102
where a tip is formed at edge portion thereof first. Interaction (attractive force or repulsive force) generating between the sample surface and the tip bends the SPM probe
102
, and the bending changes resistance value of the piezoresistor
108
formed on the SPM probe
102
. The resistance value is detected as bending quantity of the SPM probe
102
. Change of resistance value of the piezoresistor
108
is led to a signal processing portion (not shown) through the above-mentioned aluminum electrodes
114
and
116
of the metal contacting portion so as to make image as signal showing the sample surface.
At the same time as the above operation, measurement of resistance value is carried out at the reference
104
. This measurement provide reference resistance value for removing unnecessary data of changing from change of resistance value measured at the SPM probe because of changing by condition except bending of temperature and so on. Temperature compensation is realized at detecting using a bridge circuit.
The self-detecting SPM probe using the above piezoresistor is disclosed in Japanese Opened Patent No. 5-116458 and U.S. Pat. No. 5,345,815.
As above-mentioned, as a detector detecting bending quality of the SPM probe, namely the piezoresistor is formed at the probe itself in the case that the self-detecting SPM probe is used for a scanning probe microscope, complicated operation such as position adjustment of the detector like the conventional optical lever are not need at exchange of the SPM probe so as to speedily start observation of the sample.
The conventional optical lever SPM probe has been able to measure change of bending of the SPM probe based on capacitance induced by change of current flowing between a tip and a sample surface or supply of voltage which is supplied between the tip and the sample surface by the tip having conductivity. Particularly, Kelvin probe force microscope (KFM) or scanning Maxwell stress microscope is used as microscope supplying voltage between the tip and the sample surface using the conductive SPM probe and measuring voltage and the like of the sample surface.
However, the conventional optical lever SPM probe enable to measure voltage of the sample surface generally has had conductivity at only the whole SPM probe including a tip or surface thereof. As the self-detecting SPM probe forming a piezoresistor on the SPM probe can not have conductivity at the whole of SPM probe including the tip, the probe has not been used for the above KFM and SMM.
The present invention is provided in view of inconvenience the above prior art. An object of the invention is to provide an SPM probe enabling to detect bending quantity of the SPM probe by a piezoresistor formed at the SPM probe and to measure voltage a sample surface.
SUMMARY OF THE INVENTION
To solve the above-mentioned problem and achieve the object, an SPM probe according to the invention of a first aspect is characterized by that conductive film formed on is covered at said tip and near by the tip in the SPM probe comprising a lever portion which a sharpened tip is formed at edge thereof and a supporting portion for supporting the lever portion.
According to the present invention of the first aspect, as the tip has conductivity by covering the conductive film at the tip surface, it is possible that voltage is supplied between the sample being one side of electrode and the tip by taking out wiring from the conductive film for another side of electrode. As the whole of SPM prove does not have conductivity, mixing of noise can be protected.
An SPM probe according to the invention of a second aspect is characterized by that wiring is taken out from vicinity of said tip of said conductive film in the first aspect.
According to the SPM according to the present invention of a second aspect, it is possible to prevent heating of the SPM probe by voltage supply and to supply high voltage being small in loss by taking out wiring from the conductive film covering the tip surface and by selecting material being high in conductivity as wiring.
An SPM probe according to the invention of a third aspect comprises a lever portion forming a sharpened tip at edge thereof, a supporting portion for supporting the lever portion, and a bending portion connecting said lever portion and said supporting portion. The SPM probe is characterized by that conductive film is covered at said tip and vicinity thereof, insulation layer is formed on said piezoresistor and said supporting portion, and conductive layer connecting electrically to said conductive film at vicinity of said tip of said conductive film and connecting to said supporting portion through said bending portion from said lever portion in the U-shaped SPM probe passing said bending portion.
According to the present invention of the third aspect, as the probe has conductivity by covering the conductive film at the tip surface, one side of electrode is formed wiring the conductive layer from the conductive film and it is possible to supply voltage between the sample being another side of electrode and the tip. As whole of the SPM probe does not have conductivity, it is possible to prevent heating of the SPM probe by voltage supply and to supply high voltage being smal
Shimizu Nobuhiro
Shirakawabe Yoshiharu
Takahashi Hiroshi
Adams & Wilks
Dang Phuc T.
Seiko Instruments Inc.
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