JPH01216569A - Trimming method for electrostatic capacity - Google Patents

Abstract

PURPOSE:To improve the trimming accuracy of an electrostatic capacity by forming a cutout to cross a cutout and trimming it when the cutout is formed in advance on an electrode and it is trimmed. CONSTITUTION:A plurality of cutting lines 6 are initially formed from one end of an electrode 1 with laser light. In this case, since the width of a line 6 is very small, the area of the electrode 1 is not so varied, and its electrostatic capacity is not substantially altered. Then, when it is trimmed along a trimming line 4 to isolate electrodes, the capacity is reduced each time it is crossed across the lines 6 formed in advance. Further, assume that it is trimmed along the trimming line 5. In this case, if the interval between the lines 4 and 5 is DELTAX and N pieces of the lines 6 are formed in advance at an equal interval, the capacity DELTAC1 reduced each time it is crossed across the line 6 becomes the same as the fact that the length Y of the electrode becomes Y/(N+1). Accordingly, DELTAC1=DELTAC/(N+1) holds. Therefore, if it is stopped each time it is crossed across the line 6 when it is trimmed, the trimming accuracy can be improved by (N+1) times.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a capacitance trimming method, and in particular to a capacitance trimming method for trimming a capacitor provided on a semiconductor TCC substrate to a predetermined capacitance value. Regarding trimming methods.

Conventionally, a method for trimming a capacitor, which is one of the components of a semiconductor tC substrate, to a predetermined capacitance value is to cut off a part of the capacitor electrode using a laser beam for laser trimming. It was a method of adjustment.

The conventional example will be explained using FIG. 2, FIG. 3, and FIG. 4.

FIG. 2 is an external view of the capacitor before trimming. In the figure, the capacitor is composed of electrodes 1 and 2 and a dielectric 3 sandwiched between them, and when combined with other elements on the IC board, the entire IC board forms one circuit. . When mass producing these IC boards, in order to make the characteristics of each IcI board uniform, trimming is performed by shining a laser beam onto the electrodes of the capacitor and cutting off part of the electrodes using a laser trimming device. Ta. The principle of trimming will be explained using FIGS. 3 and 4.

In FIG. 3, 10 and 20 are electrodes, and 3 is a dielectric. Since the capacitance aC of the capacitor in this case is considered as a parallel plate, the lengths of each side of electrodes 10 and 20 are determined by X and Y, respectively.
When the distance between one electrode is T, it becomes C-klXY/T (1).

Here, kl is a constant.

In this case, if the electrodes are separated by applying a laser beam as indicated by the trimming line 4 in FIG. 4, X in equation (1) becomes smaller, and the capacitance C can be reduced. What is important here is that the capacitance C of the capacitor before trimming is made in advance to a value larger than the required value.

In addition, in the conventional trimming method described above, when the length X of the electrode changes by ΔX, the amount of change ΔC in the capacitance C becomes AC/C-2 ΔX/X, assuming that 2 is a constant. Therefore, AC=to 2 CAX/X...-(2).

Here, when formula (1) is substituted into formula (2), ΔC- becomes ΔXY/T·---(3), so the change lΔC is proportional to the length Y.

Here, - is 1 k2.

In formula (3), the distance T between the electrodes is constant, and the length ΔX of the electrodes separated by trimming cannot be made below a certain level depending on the positioning accuracy of the laser beam and the spot diameter of the laser beam. The conventional trimming method described above has a drawback of poor trimming accuracy.

Therefore, in order to improve the trimming accuracy, it is possible to reduce the length Y (that is, the width) of the electrode, but in that case, in order to achieve the required capacitance C, the length X must be increased. Must be. This results in a very elongated electrode, which has the disadvantage that the length X cannot be made very large due to dimensional limitations on the IC substrate.

1. An object of the present invention is to provide a capacitance trimming method that can improve capacitance trimming accuracy.

1 ■ Standing 11 The capacitance trimming method of the present invention is a capacitance trimming method in which a capacitor provided on a substrate and having electrodes facing each other is trimmed to a predetermined maximum capacitance value. The electrode is provided with a plurality of cuts in advance, and when trimming, cuts are made so as to intersect with the cuts.

K-Kou 3 Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a perspective view showing the principle of an embodiment of the capacitance trimming method according to the present invention. In Ii, 1 and 2
is an electrode, and 3 is a dielectric.

In this embodiment, first, a plurality of score lines such as 6 are made from one end of the electrode 1 using a laser beam. At this time, since the width of the notch 116 is very small, the area of the electrode 1 does not change much and the capacitance hardly changes.

Next, when trimming is performed along the trimming line 4 to separate the electrodes, the capacitance decreases each time it crosses the plurality of cuts 816 made in advance.

Further, it is assumed that trimming is performed along trimming [15,]. At this time, the interval between trimming lines 4 and 5 is ΔX1
Assuming that N cut lines 6 are placed at equal intervals in advance, the capacitance -ΔC1 that decreases each time it crosses the cut 116 is the same as when the length Y of the electrode becomes Y/(N+1). Therefore, ΔC1-ΔG/(N+1). Therefore, when trimming, the cut 16
If the capacitance is stopped every time the capacitance is crossed, the change in capacitance due to trimming will be 1/(N+1) compared to the conventional method. In other words, the trimming accuracy can be improved by (N+1) times.

In this example, trimming is performed so that the cut line drawn in advance and the trimming line drawn afterwards intersect perpendicularly; It is clear that trimming may be performed.

Furthermore, it is clear that the trimming accuracy can be further improved by increasing the number of score lines made in advance.

1g As explained above, the present invention has the effect that trimming accuracy can be improved by making a plurality of score lines perpendicular to the trimming direction in advance using a laser beam and then performing trimming. There is.

[Brief explanation of the drawing]

Figure '1 is a perspective view showing the principle of the capacitance trimming method according to the embodiment of the present invention, Figure 2 is an external view of the capacitor before trimming, Figure 3 is an external view showing the dimensions of the capacitor, and Figure 4. is an external view showing a conventional capacitance trimming method. Explanation of symbols of main parts 1.2... Electrode 3... Dielectric 4.5... Trimming line 6... Cutting line

Claims (1)

[Claims] (1) A capacitance trimming method in which a capacitor provided on a substrate and having electrodes facing each other is trimmed to a predetermined capacitance value, the electrodes having a plurality of cuts in advance. A method for trimming capacitance, characterized in that when trimming, a cut is made so as to intersect with the cut.