JPS58102535A - Electrode resistance evaluation method for micro-electrode - Google Patents

Abstract

PURPOSE:To evaluate electrode resistance of micro-electrode for ohmic contact such as LSI by actually measuring a pair of basic pattern resistances and by accurately evaluating resistance of micro-electrodes from a difference between actual measurement and calculation. CONSTITUTION:1 is a first pattern, 2 is a second pattern, 3 is an operating layer in the width of W and length of L+2d, 4 and 5 are first electrode and second electrode in the width W and length d stacked at both sides of operating layer, 6 is a third electrode in the width W, length d formed at the location isolated by l1 from the first electrode and l2 from the second electrode. It is presumed that the metal material of the first to third electrodes 4, 5, 6 has a resistivity of zero ohm and thereby an intrinsic contact resistance rc is generated when the electrodes 4, 5, 6 and the operating layer 3 are placed in contact. In this case, a resistance between the first electrode 4 and third electrode 6 of the second pattern 2 and a resistance between the second electrode 5 and third electrode 6 are calculated and an intrinsic contact resistance rcOMEGAcm<2> resulting from such contact can be calculated therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a method for evaluating the electrical resistance of a minute electrode for contact such as L8I.

(2) Background of the technology Nowadays, as the active layer shape becomes smaller, the ohmic electrodes of semiconductor devices such as L8I become smaller, and their electric resistance becomes relatively large, so that the ohmic electrodes of semiconductor devices such as L8I become smaller and the electrical resistance becomes relatively larger, so that the ohmic electrodes that could be ignored in the past cannot be ignored. It is becoming a thing.

Even if you try to measure the resistance of a rounded electrode, if the electrode is too small, you will not be able to place a measuring needle directly on the electrode, so it will be difficult to make an indirect measurement and make an accurate evaluation. There is a need for the development of evaluation methods.

(3) Conventional technology and problems The conventional evaluation method for micro-oic electrodes involves determining the inherent contact resistance of various electrode materials in large/arm-turn shapes, and calculating the value for micro-shapes by numerical calculation. I came. Therefore, as the shape becomes smaller, it is difficult to clarify and evaluate the reason why the contact resistance increases due to the rounding of the child side.

(4) Purpose of the Invention In view of the above-mentioned conventional drawbacks, it is an object of the present invention to provide an evaluation method that can accurately evaluate the electrode resistance of minute electrodes for ohmic contact in LSIs and the like.

(5) Structure of the invention and this object according to the invention, the width W and the length L+21
A first I-turn having first and second electrodes having a width w1 and a length d are provided at both ends of the active layer, overlapping the active layer, and a first I-turn similar to the first Noreen scissors and located in the middle of the active layer. A second / mother turn is formed in which a third electrode with a width W and a length d is provided at a position 1 m apart from the first electrode and 1 m from the second electrode. 1. Resistance R between the second electrodes
AIR, and the difference between them is ``All''.L...(1n, where r is the sheet resistance, t is the transport length, and R6 is the contact resistance between the active layer and the electrodes (1), (2) and (3) to calculate the contact resistance between the active layer and the electrode.

(6) Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing I-lean used in the electrode resistance evaluation method of a microelectrode according to the present invention.

In the figure, 1 is the first /? 2 is a second I9 turn, 3 is an active layer with a width W1 and a length L+2d, and 4 and 5 are a first layer with a width W and a length d formed overlappingly on both ends of the active layer.
and the second electrode, 6 is the first electrode") I-x
A third electrode having a width W1 and a length d is shown, which is formed at a position spaced apart from the electrode of s $12.

In Fig. 1, the input resistance of tml/turn l is R1
, the input resistance of the second I lean 2 is set to R1, and the input resistance of the first to third
It is assumed that the metal of the electrodes 4, 5.6 has a resistivity of θ ohm, and that the metal of the electrodes 4, 5.6 is in contact with the active layer 3.
It is assumed that a specific contact resistance rc occurs. In this case, the input resistance of each turn 1.2 including contact resistance is expressed by the following equations (1) and (2).

t.

(R13 is the resistance between the first electrode 4 and the third electrode 6 of the 26th/middle turn 2, and the resistance between the second electrode 5 and the electrode 6 of the irises 3 is
Letting the resistance between Rss (At > Am), RIIIRII becomes equations (3) and (4), respectively.

According to equations (3) and (4), the sheet resistance r of the active layer 3, (
B) is calculated using equation (5).

Here, t is the transport length defined by Clay (expressed in the second phrase).

Rc is the contact resistance (electrode resistance) in the electrode of shape dXW
Since RA>R1, the difference is ΔR1 or a7
When t is expressed by f, equations (1) and (2) become L... (7), and rearranging equation (7) yields equation (8).

(8) In the second part, W and d are determined by the Noreen shape, and r.

can be calculated using equation (5), and since ΔRA1 is a value determined by measurement, the right-hand side is a known quantity9, and the left-hand side f is an unknown quantity. Therefore, by drawing the graph of the left side of equation (8) regarding f, f can be calculated from the right side of equation (8). f is (9)
Since it is an equation, it becomes 1, de d//. Therefore, substituting this into equation (6) yields one set.

d 婁 y cm y, ,, °°゛ (To) The value of the specific contact resistance re (Ω) accompanying contact is now calculated. On the other hand, the electrode resistance town determined by the shape can be found using the formula a.

9(&sJ, Using the H formula, Rc becomes the formula (2).

Here, if we examine the tendency based on formula (8) Of, ■ /<1→
d<jv (same situation as the third electrode 6 of the second I line is not present), that is, -Q Matamachi→ω The resistance of the electrode is infinitely large.

■ f>1→d>j・(Third electrode 6 of Atsushi 2
is causing a current short circuit) r, d d d In other words, the 10I4 turn l in Figure 1 becomes the second /4 turn 2, so that the resistance zero ohm region becomes (d-24
・) It will be the same as the RC Hiroshita style.

That is, the resistance of one electrode surface becomes t. as the active layer expands, and the resistance decreases to the resistance at 9. Therefore, a good ohmic electrode is an electrode with a small L.

If the value of d is made equal to the ohmic and electrode dimensions of LSI, then
(Formula 41 fits, it becomes possible to evaluate the contact resistance with an electrode area of 8 lb.) The judgment of whether the electrode resistance is large or small can be made at the /4 turn in Figure 1 by the difference in resistance R,, R, It can be estimated by looking at .If ΔRAm (=RA-R1) is large, it is a good electrode, and if ΔR□ is small, it is a bad electrode.

If the electrode part of the pattern shown in FIG. 1 has the same electrode dimensions as the LSI, the measuring needle will not stand up, so in reality, a lead-out electrode 4 a 15 m +61 of the same shape as shown in FIG. 2 is attached. Since the lead electrodes 4 m + 5 m + 6 m have the same resistance, in the sheet resistance measurement at the second turn 2, r is calculated by subtracting the value of R11IRIm, so the influence of the lead wires is removed by the subtraction effect. Ru. The same premise holds true when evaluating the electrode resistance rcl Rc.

FIG. 3 expresses equation (8) as equation (to) and graphs the f dependence of F(1).

Using the graph in Figure 3 and equation (8), f can be found, so the transport length is 1. (t.=d//), and the specific contact resistance rC1 and the contact resistance Rc of one electrode surface (assuming the same electrode resistance) can be calculated from equation (6).

It goes without saying that evaluation can be made even if the basic pattern shown in FIG. 1 is modified and formed with different values of d.

(7) Effects of the Invention As explained in detail above, the electrode resistance evaluation method of a microelectrode of the present invention involves actually measuring the resistance of two basic/mother turns,
It is possible to accurately evaluate the minute electrode resistance of X billion by calculating the difference, and it has a great effect that it can be used for evaluating the electrode resistance of minute electrodes for ohmic and contact devices such as LSI. .

[Brief explanation of drawings]

Figures 1 and 2 are diagrams for explaining the basic 9 turns for the electrode resistance evaluation method of microelectrodes according to the present invention.
The figure is a graph of /knee F (/') used in the evaluation process of the microelectrode electrode resistance evaluation method according to the present invention. In the drawings, 1 and 2 are basic gutters, 3 is an active layer, 4.5.6 is an electrode, and 4m + 5m + 6m is an extraction electrode, respectively. Figure 1 弗 2nd 弗 3 Same f (=%0)

Claims (1)

[Claims] 1. First and second electrodes each having a width W1 and a length 4 are provided at both ends of an active layer having a width W and a length L+21 so as to overlap the active layer, and have nine and tenth non-turns; The first electrode L1 and the second electrode F are arranged in the middle of the active layer.
A second arm is formed with a third electrode having a width W1 length at nine positions h apart, and the first arm of each arm turn is formed.
．． Measure the resistance R, , R, between the second electrodes a, and the difference Δ”
AI〉t・-(1) where r is the sheet resistance, t・ is the transport length, and Rc is the contact resistance between the active layer and the electrode (1) * Using equations (2) and (3), calculate the active layer and 1. A method for evaluating electrode resistance of a microelectrode, comprising: calculating a contact resistance Rc between electrodes.