JP3722133B2 - Evaluation method and evaluation apparatus for junction potential of dissimilar metals - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an evaluation method and an evaluation apparatus related to a junction potential of dissimilar metals in a multilayer wiring of a semiconductor device.
[0002]
[Prior art]
As semiconductor devices are further miniaturized, multilayered, and integrated, the influence of the potential of a minute portion such as a contact portion in the multilayer wiring on the operation quality of the semiconductor device is increasing. In particular, the influence of the junction potential of dissimilar metals in the contact portion can no longer be ignored, and the realization of a measurement method and a measurement apparatus related to the above is desired. For this reason, a measurement method related to contact resistance has been proposed (see, for example, Patent Document 1).
[0003]
A conventional example will be described below with reference to the drawings. FIG. 6 is a circuit diagram for contact resistance measurement of a conventional example. As shown in FIG. 6, in the conventional example, two contacts 13 connecting the conductive diffusion layer 11 and the aluminum wiring 12 are set as one contact row CA1 to CAn, and one end of each contact row is connected to the input terminal 14. It is characterized in that it is connected and the other end is an open end 15 by an aluminum wiring 12.
[0004]
According to the above configuration, when a rectangular pulse is applied to the input terminal 14, each open end 15 of the contact rows CA1 to CAn has a waveform corresponding to CR which is the product of the capacitance value C and the resistance value R of the circuit. Appears. The rise time tr of this waveform is equal to CR. From this, the resistance value R is obtained from the value of the time tr obtained from the measurement, using the capacitance value C that is uniquely determined from the shape of the circuit and the dielectric constant of the material.
[0005]
[Patent Document 1]
JP-A-8-78493 [0006]
[Problems to be solved by the invention]
However, in the above-described conventional example, the capacitance value C uniquely determined from the circuit shape and the dielectric constant of the material is obtained. However, it is almost impossible to specify the capacitance value C with a highly accurate numerical value from the complicated shape of the circuit of a recent highly miniaturized semiconductor device. Moreover, the dielectric constant of the material is not uniform throughout the circuit, and it can be said that it is almost impossible to obtain the dielectric constant in order to obtain a highly accurate capacitance value C.
[0007]
Further, when a rectangular pulse is applied to the input terminal, the rising time tr at the open end is measured, and the resistance value R is obtained using the capacitance value C, assuming that the rising time tr is equal to CR. Become. However, it can be said that it is almost impossible to obtain the resistance value of the target contact portion with high accuracy from the resistance value R obtained by this method.
[0008]
In view of such circumstances, the present invention provides an evaluation apparatus and an evaluation method related to a junction potential of dissimilar metals that make it possible to measure contact resistance in multilayer wiring with high accuracy.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the evaluation method for the junction potential of dissimilar metals according to the present invention is a method for evaluating a multilayer wiring having a junction of dissimilar metals, in which a plurality of taps having the same structure are installed on the wiring near the contact portion. The potential difference between the taps is measured with a plurality of applied current values such that Joule heating is negligible, and the initial potential when the applied current value is 0 is obtained from the correlation of the potential difference with respect to the applied current value by the least square method, The junction potential distribution near the contact portion is obtained.
[0010]
In the above evaluation method, the temperature of the contact part and the wiring is adjusted by a heat source, the temperature of the contact part and the wiring is compared, and it is confirmed that the influence of Joule heat generation from both is negligible. It is preferable to obtain the dependent initial potential and junction potential distribution.
[0011]
Further, the evaluation apparatus for the junction potential of different metals according to the present invention is a multi-layer wiring evaluation apparatus having a junction of different metals, and includes a plurality of taps of the same structure installed on the wiring in the vicinity of the contact portion, the contact portion and the wiring. A current source for applying a current, a voltmeter for measuring a potential difference between the taps, a heat source for adjusting the temperature of the contact part and the wiring, a temperature sensor installed in the vicinity of the contact part and the tap, a current source and a voltage And a controller analyzer for controlling the heat source and the temperature sensor. The controller analyzer has an initial potential when the applied current value is 0 by the least square method based on the correlation of the potential difference with respect to the applied current value of the current source. And the junction potential distribution near the contact portion is obtained.
[0012]
According to the above configuration, the junction potential of the dissimilar metal in the contact portion can be accurately evaluated with a simple configuration, so that the contact resistance in the multilayer wiring can be measured with high accuracy.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
(First embodiment)
FIG. 1 is a cross-sectional view in the vicinity of a contact portion of a semiconductor device showing an embodiment of a method for evaluating a junction potential of dissimilar metals in a semiconductor device according to the present invention.
[0015]
Taps 23a, 23b, 23c and 23d having the same structure are formed in the vicinity of the contact portion 22 of the multilayered wiring 21 in the semiconductor device, and each of the taps 23a-23b, between the taps 23a-23c, and between the taps 23a-23d. The potential is measured at a plurality of applied current values with a plurality of applied current values such that Joule heat generation can be ignored. The wiring temperature at this time is room temperature because Joule heat generation near the contact portion 22 and the wiring 21 can be ignored.
[0016]
FIG. 2A is a diagram showing an initial potential obtained from each inter-tap potential by the least square method. As shown in FIG. 2A, the horizontal axis indicates the current value applied to the contact portion 22 and the wiring 21, and the vertical axis indicates the potential difference between the taps 23a-23b, between the taps 23a-23c, and between the taps 23a-23d. The initial potential when the applied current value is 0 is obtained by the least square method.
[0017]
FIG. 2B is a graph showing the junction potential distribution at each tap installation position. As shown in FIG. 2B, the initial potentials of the taps 23a-23b, the taps 23a-23c, and the taps 23a-23d obtained in FIG. And the distance of the tap 23d from the tap 23a is plotted on the horizontal axis. FIG. 2B shows the junction potential distribution in the vicinity of the contact portion 22.
[0018]
According to the above configuration, the initial potential of the contact portion 22 and the junction potential distribution on the wiring 21 can be obtained with high accuracy. In other words, the junction potential of different metals in the contact portion 22 can be accurately measured by a simple method.
[0019]
(Second Embodiment)
FIG. 3 is a cross-sectional view in the vicinity of a contact portion of a semiconductor device showing an embodiment of a method for evaluating a junction potential of different metals depending on the temperature of the semiconductor device according to the present invention.
[0020]
A temperature sensor at a position where the temperature of the contact portion 42 and the wiring 41 is adjusted by a heat source of a hot chuck and current is applied from a current source so that the influence of Joule heat generation from the contact portion 42 and the wiring 41 can be almost ignored. The temperature is compared by T1) 43 and temperature sensor (T2) 44, and it is confirmed that Joule heat generation of the contact portion 42 and the wiring 41 can be ignored. Next, taps 45a, 45b, 45c and 45d having the same structure installed in the vicinity of the contact portion 42 of the multilayered wiring 41 in the semiconductor device, respectively, between the taps 45a-45b, between the taps 45a-45c, and between the taps 45a-45d. The potential difference is measured with a plurality of applied current values. This measurement is performed in a plurality of temperature environments.
[0021]
FIG. 4A is a diagram showing the initial potential obtained by the least square method from the potentials between the taps when the measured temperature is changed to t1, t2, and t3. As shown in FIG. 4A, for each measurement temperature t1, t2, t3, the current value applied to the contact portion 42 and the wiring 41 is plotted on the horizontal axis between taps 45a-45b, between taps 45a-45c, and tap 45a. Each potential difference between −45 d is plotted on the vertical axis, and the initial potential when the applied current value is 0 is obtained by the least square method.
[0022]
FIG. 4B is a graph showing the junction potential distribution according to each tap installation position when the measured temperature is changed to t1, t2, and t3. As shown in FIG. 4B, the taps 45a-45b, taps 45a-45c, and taps 45a-45d when the measured temperatures obtained in FIG. 4A are changed to t1, t2, and t3. The initial potential between each of them is plotted on the vertical axis, and the distance of the tap 45b, tap 45c and tap 45d from the tap 45a is plotted on the horizontal axis. FIG. 4B shows the junction potential distribution in the vicinity of the contact portion 42.
[0023]
According to the above configuration, the initial potential of the contact portion 42 and the junction potential distribution on the wiring 41 depending on the temperature of the semiconductor device can be obtained with high accuracy. In other words, the junction potential of the dissimilar metal in the contact portion 42 can be accurately measured by a simple method.
[0024]
(Third embodiment)
FIG. 5 is a cross-sectional view of an evaluation apparatus for realizing the above-described method for evaluating the junction potential and junction potential distribution of dissimilar metals.
[0025]
A plurality of taps 63 are installed in the vicinity of the contact portion 61 and the wiring 62, a temperature sensor (T1) 64 is installed in the vicinity of the contact portion 61 and the wiring 62, and Joule heat is generated from the vicinity of the contact portion 61 and the wiring 62. A temperature sensor (T2) 65 and a hot chuck 66 as a heat source are installed at a position where the influence can be almost ignored. Further, a voltmeter 68 capable of measuring a potential difference between the current source 67 for applying a current to the contact portion 61 and the wiring 62 and each tap 63 is provided.
[0026]
According to the above configuration, the temperature sensor (T1) 64, the temperature sensor (T2) 65, the hot chuck 66, the current source 67 and the voltmeter 68 are controlled by the controller analyzer 69, and the obtained temperature, applied current value, and The controller analyzer 69 can accurately obtain the initial potential when the applied current value of the contact portion 61 is 0 and the junction potential distribution on the wiring 62 by the controller analyzer 69 using the least square method. In other words, the junction potential of dissimilar metals in the contact portion 61 can be accurately evaluated with a simple configuration.
[0027]
【The invention's effect】
As described above, according to the evaluation method and the evaluation apparatus related to the junction potential of different metals according to the present invention, the junction potential of different metals in the contact portion can be accurately evaluated with a simple configuration. It makes it possible to measure the resistance with high accuracy.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of the vicinity of a contact portion of a semiconductor device according to a first embodiment of the present invention. FIG. 2A is a diagram showing an initial potential in the first embodiment. FIG. 3 is a cross-sectional view in the vicinity of a contact portion of a semiconductor device in a second embodiment of the present invention. FIG. 4A is a diagram showing an initial potential in the second embodiment. FIG. 5 is a cross-sectional view of an evaluation apparatus according to a third embodiment of the present invention. FIG. 6 is a circuit diagram for measuring contact resistance in a conventional example.
DESCRIPTION OF SYMBOLS 11 Conductive diffusion layer 12 Aluminum wiring 13 Contact 14 Input terminal 15 Open end 21 Wiring 22 Contact part 23a Tap 23b Tap 23c Tap 23d Tap 41 Wiring 42 Contact part 43 Temperature sensor (T1)
44 Temperature sensor (T2)
45a Tap 45b Tap 45c Tap 45d Tap 61 Contact portion 62 Wiring 63 Tap 64 Temperature sensor (T1)
65 Temperature sensor (T2)
66 Hot chuck 67 Current source 68 Voltmeter 69 Controller analyzer

Claims (3)

In the evaluation method of the multilayer wiring having the junction of different metals,
Install multiple taps with the same structure on the wiring near the contact part,
Measure the potential difference between the taps at a plurality of applied current values such that Joule heating is negligible,
From the correlation of the potential difference with respect to the applied current value, an initial potential when the applied current value is 0 is obtained by a least square method, and a junction potential distribution in the vicinity of the contact portion is obtained. Evaluation method regarding. Adjusting the temperature of the contact part and the wiring with a heat source;
Compare the temperature of the contact part and the wiring to confirm that the effects of Joule heat from both can be ignored,
2. The evaluation method for the junction potential of dissimilar metals according to claim 1, wherein the initial potential and the junction potential distribution depending on the temperature in the vicinity of the contact portion are obtained. In an evaluation apparatus for multilayer wiring having junctions of dissimilar metals,
A plurality of taps of the same structure installed on the wiring near the contact part,
A current source for applying a current to the contact portion and the wiring;
A voltmeter for measuring a potential difference between the taps;
A heat source for adjusting the temperature of the contact portion and the wiring;
A temperature sensor installed in the vicinity of the contact portion and the tap;
A controller analyzer that controls the current source, the voltmeter, the heat source, and the temperature sensor;
The controller analyzer obtains an initial potential when the applied current value is 0 by a least square method from a correlation of the potential difference with respect to an applied current value of the current source, and obtains a junction potential distribution near the contact portion. An apparatus for evaluating the junction potential of dissimilar metals.

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