JPS6028366B2 - How to adjust resistance elements - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for adjusting a resistive element, and more particularly to a method for laser trimming a thin-film or thick-film rectangular resistive element into an L-shape.

Generally, in order to adjust the resistance value of a thin film or thick film rectangular resistance element by laser trimming, a method as shown in FIGS. 1A to 1C is performed.

FIG. 1A is called an L-cut, in which an L-shaped notch 3 is made in the resistance element 1 attached to the electrode 2. Similarly, figure B shows a straight cut in which a single straight notch 3 is formed in the resistance element 1, and figure C shows a so-called S cut in which a straight line notch 3 is formed in the resistance element 1. Normally, the adjustment of a rectangular resistance element is performed by L-cutting because the resistance element has less local concentration of current, and the lower the sensitivity during adjustment, the better. This method of adjusting the resistance value by L-cut will be explained with reference to FIG. is the horizontal portion (hereinafter, the length of the B cut, C is the distance from the electrode 2 to the L cut start point, and W is the width of the notch made by the laser beam).

In L cut, 9-bit conversion of trimming direction 89
Deciding the point (hereinafter referred to as the break point) is an important problem, and conventionally, '1
The length of A cut to the first fold point is A = WQ (Q = 0.2
~0.6), there is a method of determining from the width of the resistor element 1, and a method of determining it from the width of the resistor element 1, {2-, where the target resistance value is Ro, the resistance value at the break point of the L cut is Rt, and Rt is 50 of Ro. ~7
There is a method in which the point where the value reaches 0% is taken as the breaking point.

However, the initial value Ri of the resistor element 1 shows different values depending on the specific resistance of the resistor film, variations in film thickness pattern formation, etc., so as in the former method, the length of the A cut is From the width W, A=QW (Q=0.2~
0.6), for example, in a resistor element whose initial resistance value Ri is close to the target resistance value Ro, the resistance value Rt will reach the target resistance value Ro before the trimming direction is changed, and the resistance value will simply be This results in a straight cut, causing concentration of current near the bending point, which may lead to deterioration of the element. Furthermore, in a resistance element whose initial resistance value Ri is considerably lower than the target resistance value Ro, the B cut reaches the electrode section 2 before reaching the target resistance value Ro. Trimming may not finish. In the latter method, if the resistance value Rt at the break point is set to 50 to 70% of the target resistance value Ro, for example, in a resistance element whose initial resistance value Ri is larger than the resistance value Rt at the break point,
It is a straight cut and no L cut is made. Therefore, an object of the present invention is to solve the drawbacks that the conventional L-cut method for adjusting a resistance element results in a straight cut, which causes local concentration of current in the resistance element and unadjustment of the resistance value. Removed to ensure an L cut,
Furthermore, it is an object of the present invention to provide an adjustment method that allows the length of the B cut to be constant regardless of the initial resistance value.

Generally, the resistance value R of a rectangular resistance element with length L and width W is given by the sheet resistance value Rs and the aspect ratio (=L/W) as Ns.
R=R3-Voice=RSNS Represented by '1'.

When this rectangular resistance element is L-cut, the sheet resistance R
Since s does not change, the resistance value ∊′ is R as in equation 1).
=RsNs' {21, where Ns'(R'/Rs) is usually called the equivalent aspect ratio.

It is known that the equivalent aspect ratio of an L-cut rectangular resistance element can be determined by a calculation method for electric field distribution called the "relaxation method," which is a well-known numerical analysis method. pp. 56-62, 1973” (
Processing of Electronic C
Ompo ship nG Con re ratio pp56-62,
1973)).

The resistance element adjustment method of the present invention is based on the resistance value at the break point calculated by the relaxation method when an L cut is made on a thin film or thick film rectangular resistance element so that the length of the B cut is always constant. Between Rf and initial resistance value Ri, Rt=QRi+3
(Q, 8 are constants) Based on the property that a linear relationship of '3' is established, from the initial resistance value Ri of the resistance element,
The feature is that the resistance value Rt at the break point is determined, and when the resistance value reaches Rt, the trimming direction is changed and an L cut is performed.

Next, embodiments according to the present invention will be described with reference to the drawings. An embodiment of the present invention is shown in FIGS. 2A to 2D. In Figure 2 A, length L is 2, 35 side width W is 1.7 ribs, target resistance value R
o is 300Q, the distance C from the electrode 2 to the trimming start point is 0.475, and the width of the notch by the laser beam is set so that the cut length B is a constant value of 0.9. This shows the case of making an L cut with a W of 0.05 sail. First, the equivalent aspect ratio N after B-cut of rectangular resistance element 1 is
f and the equivalent aspect ratio Nt after the cut is completed, A cut length is 0
．． Six points between the 2 side and the 1.2 side were determined using the above-mentioned "relaxation method." If the target resistance value Ro is obtained by these L cuts, then the rectangular resistance element 1
The sheet resistance value Rs of
'41.

Therefore, at this time, the initial resistance value Ri is calculated by the formula '11, {4 Ri = RS - voice = Batei・Koboshi (51), and the break point resistance value Rt is calculated by the formula '21, '4', Rt=RSNt=Kai Nt {6'.

Based on the above results, Table 1 shows the values of Nf and Nt of the rectangular resistance element 1, and the values of Rs, Rj, and Rt calculated from equations {4' to (6}), using the A cut length as a variable factor.

Table 1 Next, when the values of Ri and Rt are plotted on a graph, the second
As shown in Figure B, the linear relationship Rt=QRi+8 was obtained, so the values of Q and 8 were determined by the least squares method,
Rt = 0.515 tuna i + 140.6 (Q)
I asked for the.

Note that even when the cut length was changed by 8, the linear relationship of Rt=QRi+8 was maintained unchanged, although the values of Q and B were different.

For trimming, first, the initial resistance value Ri of the resistance element 1 was measured, and the resistance value Rt at the break point was calculated from the above equation. Next, trimming is started while detecting the resistance value of the resistor element 1, and when the resistance value reaches Rt, the trimming direction is changed to 9.
00, and when the target resistance value reached 3000, trimming was stopped. FIG. 2C shows the locus of the L cut when the initial resistance value Ri of the resistance element 1 is 108.80. At this time, the resistance value Rt at the corner point is 196.70
, the length of the A cut was 1.25 ribs. FIG. 2D shows the locus of the L cut when the initial resistance value Ri of the resistance element 1 is 232.6Q, and the resistance value Rt at the break point is 260.60,
The length A of the A cut was on the 0.50 side. The length of the B cut was a constant value of about 0.9 legs in all cases, and the resistance value after adjustment was also within 0.1% of the target resistance value of 3000. A second embodiment according to the present invention is shown in FIGS. 3A to 3D.

``In Figure 3 A, the length L is 1.5 ribs, the width W is 2.5 ribs, the target resistance Ro is 390, and the resistance element 1 has a constant value of 0.5 pigs. As shown in FIG. Using the same method as in the case above, the values of Nf, Nt, Rs, Ri, and Rt were calculated for the four points of the A-cut length of this rectangular resistance element from 0.25 skin to 1.75 skin. Table 2: Next, when the values of Ri and Rt were plotted on a graph, as shown in Figure 3B, a linear relationship of Rt = QRi + 8 was obtained as in the first example. , determine the values of Q and 3 by the least squares method, Rt = 0.293 fox i + 26.
88(Q) ■ was calculated.

Note that even when the B cut length was changed, the linear relationship between Ri and Rt was maintained as in the first example.

Trimming was performed in the same manner as in the first example. In FIG. 3C, the initial resistance value Ri of the resistance element 1 is 13.8.
The locus of the L cut in the case of 0 is shown. At this time, the resistance value Rt at the break point was 30.90, and the A-cut length A was on the 1.75 side. FIG. 3D shows the initial resistance value Ri of the resistance element 1.
In the locus of the L cut when is 32.80, the predetermined resistance value Rt was 36.50, and the length A of the A cut was 0.5 skin. In either case, the length of the B cut is a constant value of approximately 0.5 skin, and the resistance value after adjustment is also the target resistance value 390.
It was within 0.5% of soil. For the rectangular resistance elements 3 of different shapes with a constant B cut length, Nf and Nt are calculated using the same method as in the first and second embodiments, and LRt is calculated.
The relationship between Rt and Rj was determined, and a linear relationship of Rt=QRj+B was obtained in both cases.

Therefore, it was confirmed that this linear relationship is an inherent property of a rectangular resistance element that is L-cut with a constant B-cut length.

The length of the B cut in each example deviated from the set value due to variations in pattern formation of the resistive element, alignment errors of the laser trimming device, resistance measuring device, etc., but in any case. Also, the deviation was within a negligible range with respect to the length of the B cut.

Resistance elements adjusted by this method have no local current concentration due to incomplete L-cuts or unfinished trimming, and L-cuts are reliably performed, and the length of B-cuts is equal to the initial resistance value. remained constant regardless of

This is because the resistance value adjustment method using L-cut of the present invention is
When an L cut is made on a thin film or thick film rectangular resistance element so that the length of the B cut is constant, the difference between the initial resistance value Ri and the resistance value Rt at the break point is Rt=QRi18 (Q,
8 is a constant) This effect is thought to be due to the application of the property that there is a linear relationship.

In the method of adjusting a resistance element that becomes an L cut according to the present invention, the length of the B cut can be made constant regardless of the initial resistance value, so within the allowable range of variation such that the B cut does not reach the electrode. If the length of B cut is increased, then,
It is possible to make the widest remaining L cut at that initial resistance value.

Therefore, the present invention is an adjustment method that can produce a resistor element that is stable over time and has the least thermal influence of the laser beam on the resistor. Furthermore, since it is possible to maximize the area of the resistive element, the present invention can of course provide a method for adjusting the resistive element with the maximum allowable power consumption.

[Brief explanation of the drawing]

1A to 1C are plan views illustrating various cutting methods for adjusting the resistance value, and FIGS. 2A to 2D are plan views showing an embodiment according to the present invention, FIGS. 3A to 3D are plan views showing other embodiments of the present invention. In the figure, 1... resistance element, 2... electrode, 3. ．．・．． ...This is the trajectory of the L cut. Younger brother' drawing Younger brother Z drawing Tsutomu 3 drawing

Claims (1)

[Claims] 1 Thin film or thick film rectangular resistance element is laser-coupled into an L-shape.
In the method of adjusting the resistance value by trimming, the L
From the trimming direction change point in glyph trimming,
The resistance value of the direction change point is determined from the initial resistance value of the resistance element so that the distance to the trimming end point becomes a predetermined constant value, and the resistance value of the resistance element reaches this resistance value. A method for adjusting a resistive element, characterized in that when the trimming direction is changed, the trimming direction is changed and trimmed.