JPH01253206A - Method of trimming resistor film - Google Patents

Abstract

PURPOSE:To prevent dust from being produced by shortening the time for trimming by forming a notch in a resistor film along a line surrounding a region of the resistor film to be removed and prohibiting said region from being supplied with a power after the formation of the notch. CONSTITUTION:Resistance between electrodes 11 and 12 are monitored, and at the same time a notch 14a is formed from one marginal edge of a resistor film 13 toward a direction normal to a straight line which defines an interelectrode distance. Then, the direction of the notch 14b is changed, and a new notch 14b is formed in a direction parallel to the straight line defining the distance between the electrodes 11 and 12. The notch 14b is extended, with the resistance between the electrodes 11 and 12 being monitored, to its length where the resistance is accurately purposed one. Thus, the resistor film 13, in which the resistance between the electrodes 11 and 12 is the purposed one, is yielded. Hereby, trimming time is shortened to prevent any dust from being produced.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to trimming of a resistive film in which a part of the resistive film formed between electrodes is removed to correct the resistance value between the electrodes. Regarding the method.

[Prior art] For general resistance elements, variable resistance elements, resistors such as potentiometers, or integrated circuits such as hybrid ICs, a resistive thin film is formed on the surface of an insulator and this is interposed between electrodes. A resistive film is used.

Usually, with this resistive film, it is not necessarily possible to obtain the desired resistance value simply by forming a resistive thin film on the surface of the insulator, so after forming the thin film, a part of the thin film is removed to increase the resistance value. Trimming to correct to the desired value is tolerated.

That is, in general, in the above-mentioned resistive film, first, a thin film is formed such that the resistance value approximately determined from the thickness and area of the film is always lower than the target resistance value, and then the above-mentioned resistance film is formed. While measuring the resistance value between the electrodes, trimming is performed to remove a part of the thin film to obtain the desired resistance value.

FIGS. 6 to 8 are diagrams showing resistive films subjected to the conventional trimming method.

The resistive film shown in FIG. 6 is formed by the conventionally most commonly used method, in which a resistive film 3 is formed between electrodes 1 and 2, and then a resistive film 3 is formed between electrodes 1 and 2. While measuring the resistance value between the electrodes, make a cut 4 in a direction perpendicular to the straight line that defines the distance between the electrodes, and make an extension 1 of this cut 4.
? [[ is adjusted so that the resistance value between the electrodes becomes a desired value.

This method has the advantage that only a relatively narrow cut 4 is made and the extension distance is adjusted, so that the area to be removed is small and the adjustment is relatively easy to control. Therefore, for example, using a relatively low output laser device, a laser beam is focused to a diameter of about several tens of μm, and the laser beam is irradiated to a predetermined portion of the resistive film 3 through a reflecting mirror, and the resistance between the electrodes is By changing the set angle of the reflection jJ1 while measuring the value, the irradiation position can be controlled, thereby making it possible to form the desired incision 4 extremely quickly.

However, when a current is passed through the resistive film 3 in which the notches 4 are formed by this method, the current flows at a point 4b where the tip 4a of the notch 4 and the extension line of the notch 4 intersect with the edge of the resistive film 3. Therefore, the allowable wattage of the entire resistive film is regulated by the maximum current that can flow through this area, and the relatively large area of the resistive film pond is The disadvantage is that most of the parts that have this are wasted. This point becomes an extremely serious obstacle when increasing the density of integrated circuits, for example.

Therefore, the area of the resistive film 3 is used as effectively as possible,
In order to obtain a small resistive film with a large allowable matte number, a method has been considered in which a part of the region 5 of the resistive film 3 is removed, as shown in FIG.

For example, in the case of a potentiometer, etc., when the horizontal axis is the distance between the point on the curve through which the moving electrode passes and the one electrode, and the resistance value between these points and the electrode is taken as the reduced axis. Even in the case of obtaining a resistive film in which the relationship between these distances and resistance values accurately conforms to a predetermined curved relationship f, the above-mentioned method of providing notches cannot be applied.
The method of removing the above-mentioned part of the area has been applied.

FIG. 8 is a diagram for explaining a trimming method performed when manufacturing a potentiometer. In the figure, a movable electrode 6 is provided on a resistive film 3 formed between electrodes 1 and 2. During trimming, this moving electrode 6
While measuring the resistance value between the electrode 6 and the one electrode 1, a partial region 5 of the resistive film 3 is removed so that the measured resistance value becomes a predetermined value at each position on the resistive film of the electrode 6. Ru. That is, by performing this operation up to the vicinity of the other electrode 2, a potentiometer having a predetermined resistance curve can be obtained.

[H u to be Solved by the Invention] However, in the trimming method carried out to obtain the resistive films shown in FIGS. 7 and 8, the removal area of the resistive film is large, so the trimming process takes a considerable amount of time. This method requires time and has the drawback that control to accurately remove a region having a desired size so as to obtain a desired resistance value is not necessarily easier than when the above-mentioned notches are provided.

That is, for example, in the case of using a laser beam as in the method of forming a notch, the area of the removed region is accurately adjusted to accurately match the correction value to the desired resistance value, and the boundary of the removed region is made clear. In order to prevent changes in the area over time, the diameter of the laser beam must be narrowed down, and as a result, the area that can be removed with one beam scan is limited, requiring multiple scans, and each scan It was difficult to control the direction of the

In addition, trimming when manufacturing a potentiometer as shown in FIG. 8 is generally performed by a cutting method using a drill, or a so-called sand blasting method in which alumina powder is jetted from a nozzle and sprayed onto the area to be removed. However, they all take a long time to process, generate a large amount of cutting chips and dust that are harmful to the product, and also have many sharp protrusions on the edges of the resistive film after processing. These protrusions may peel off later and cause problems, and in order to prevent such protrusions from occurring, the machining pitch p (see Figure 8) should be reduced. Attempting to make the shape smooth has the disadvantage that the processing time becomes even longer.

An object of the present invention is to provide a method for trimming a resistive film that eliminates the above drawbacks.

[Means for Solving the Problems] The present invention does not involve removing the entire region of the resistive film to be removed, but rather removing the entire region of the resistive film along a line surrounding the region of the resistive film to be removed in at least a part of the dashed line. forming a notch in the resistive film across the area, such that the region to be removed, which contributed to conduction between the electrodes before the notch was formed, no longer contributes to the conduction after the notch is formed; It is possible to obtain the same effect as when the entire area to be removed is not removed, thereby making it possible to significantly shorten the trimming time and suppress the generation of dust, etc.
It has the following configurations.

(1) In a resistive film trimming method in which the resistance value between the electrodes is corrected by removing a part of the resistive film formed between the electrodes, a chain line is formed along a line surrounding a region of the resistive film to be removed. A cut is formed in the resistive film over at least a part of the section, and the region to be removed, which contributed to the conduction between the electrodes before the cut was formed, becomes less conductive after the cut is formed. A method for trimming a resistive film, characterized in that the resistance value between the electrodes is modified so that vr is no longer applied to the resistive film.

(2) In a resistive film trimming method in which the resistance value between the electrodes is corrected by removing a part of the resistive film formed between the electrodes, a unit section serving as a reference is provided in the resistive film, From one edge of the two edges of the resistive film other than the edge connected to the electrode toward the center of the resistive film so that the resistance value of the section becomes a reference unit resistance value. , a reference cut is provided by removing a region spanning the section, and then a position is spaced from the tip of the reference cut toward one of the electrodes by a unit distance equal to the section distance of the unit section. Next, the resistance value of the section of the resistive film in which the correction notch is formed is compared with the reference unit resistance value, and then, the direction of extension is determined based on the comparison result. The correction notch is further extended by a unit distance from the tip of the correction notch, and the resistance value of the section where the correction notch is provided is compared with the reference unit resistance value in the same manner as above. A method for trimming a resistive film, characterized in that the resistance value of the resistive film is corrected by determining the extension direction based on the comparison result and reversing the steps of providing correction incisions one after another.

[Function] According to the above configuration (1), when a notch is provided in the resistive film along a line surrounding the area to be removed, the part provided with this notch is separated from the other part with the notch as a boundary. electrically insulated between the In this case, if the section in which the cut is provided exceeds a certain range, the region to be removed, which contributed to the conduction between the electrodes before the cut was provided, no longer contributes to the conduction.

Therefore, by simply forming the incision without removing the entire area to be removed, it is possible to obtain the same effect as when the entire area to be removed is removed.

Further, according to the above configuration (2), by forming the reference notch, a unit section serving as a reference having a reference unit resistance value is formed.

Next, a correction notch is formed by a unit distance from the tip of the reference notch, and a resistance value from the reference line to the tip of the correction notch is measured.

In this case, when the resistive film has negative resistance characteristics, the difference between the measured resistance value and the reference unit resistance value should be zero, and when the characteristics change, It will show a value according to the change in its characteristics.

Therefore, if these values are compared, the extension direction is determined based on the comparison result, and the correction notch is further extended by a unit distance from the tip of the correction notch, the resistance of the resistive film will be increased by this extended length. The value takes into account the change in the characteristics.

Therefore, as in the above configuration, by repeating the same steps as above one after another to correct the resistance value of the resistive film, each point on the straight line from one electrode to the other electrode in the resistance rise can be adjusted. If the distance between and the one electrode is plotted on the horizontal axis, and the resistance value between these points and the electrode is plotted on the vertical axis, the relationship between these distances and the resistance value will be exactly a predetermined curved relationship. A resistive film formed in this manner can be obtained relatively quickly and easily.

[Example] FIG. 1 is a diagram for explaining a method for trimming a resistive film according to an example corresponding to claim (1) of the present invention.

In FIG. 1, numerals 11 and 12 are electrodes, and numeral 13 is a resistive film formed between the electrodes 11 and 12.

The trimming method of this embodiment obtains the same effect as when the cut 14 is formed in the resistive film 13 and the entire region 15 to be removed is removed, and is carried out in the following steps.

First, while monitoring the resistance value between the electrodes 11 and 12, a cut 14a is formed from one edge of the resistive film 13 in a direction perpendicular to the straight line defining the distance between the electrodes.

In this case, the length of this notch 14a is determined by observing how much the resistance between the electrodes changes when this notch is formed by a predetermined short distance, and based on the result. Roughly calculate the length such that when the electrodes are moved in parallel and the entire area through which this cut passes is removed, the resistance value between the electrodes becomes approximately the desired resistance value, and the calculated value is Form it to the desired length.

When the cut 14a has a predetermined length, the direction of the cut is changed to be parallel to the straight line defining the distance between the electrodes, thereby forming a cut 14b. This cut 14b is extended while monitoring the resistance value of the electrode 1m, and is set to a length such that the resistance value accurately reaches the desired resistance value.

Thereby, it is possible to obtain a resistive film 13 in which the resistance value between the electrodes 11 and 12 becomes the desired resistance value.

In this case, if the cut 14c shown by the dotted line in FIG. 1 is provided to completely form the grt region 15 to be removed into an island shape, it is possible to completely eliminate the possibility of troubles caused by stray current or the like.

According to this embodiment, just by forming the notch 14, the same resistance value modification effect can be obtained as in the case where the entire region 15 surrounded by the notch 14 is removed.

This makes it possible to perform trimming extremely quickly and easily using the laser method or the like described above.

Furthermore, generation of dust and the like can be significantly suppressed during this trimming.

FIGS. 2 and 3 are diagrams for explaining a method for trimming a resistive film according to an embodiment corresponding to claim (2) of the present invention.

In the figure, numerals 21 and 22 are electrodes, and numeral 23
is a resistive film formed between these electrodes [21 and 22].

The trimming method of this embodiment is an example that can be applied when manufacturing a potentiometer, etc.
A cut 24 is formed in the area 24 to obtain the same effect as when all the area 25 to be removed is removed, and thereby the movable type @26 moves from one electrode 21 to the other electrode 22 and the one electrode [! These moving type f! 26 and the electrode 21 on the vertical axis, the relationship between these distances MX(θ) and the resistance iR is exactly the desired curved relationship (for example, R=aX or R= The purpose is to obtain a resistive film formed so as to have a linear coefficient represented by aθ (where a is a constant), and the following steps are performed.

First, a straight line including the edge on the right side in the figure of the one electrode 21 is shown.
aS and the other electric current f! of the T4'ffl from this straight line S! 22 by a unit distance ΔX (represented by Δθ in the case of a rotary potentiometer) as a reference unit interval, and the type f! of the resistive film 23 is defined as a reference unit interval. 21.22
By removing a region spanning the section from one edge (the edge located at the bottom in the figure) of the two edges other than the edge connected to the resistive film 23 toward the center part of the resistive film 23, A reference cut 24a is provided, and this reference cut 24
By adjusting the extension distance of a, the resistance value of the reference unit section ΔX (Δθ) is made to become the reference unit resistance value Δr.

This work uses the moving electrode 26 as the reference! Δ from lS
The resistor WA23 is set at a position X apart and the resistance value between them is monitored while the resistor WA23 is irradiated with a processing laser beam to remove the resistive film in the section little by little. This is performed by continuing until the value reaches the reference unit resistance value Δr.

At this time, the unit distance ΔX (Δθ) and the reference unit resistance value Δr are, for example, the length of the resistive film formed between the electrodes XO (represented by θ0 in the case of a rotary potentiometer), and the distance between these electrodes. Let the target resistance value be RQ, and further assume that the resistance value between the one electrode 21 and the moving electrode 26 has a linear relationship with the distance between these electrodes, In the case of the above-mentioned linear relationship, a in the equation R=aX (or R=aθ) is a=
Since Ro/XO (or a=Ro/θ0) and R=Δr, X=ΔX (or θ=Δθ), Δr=aΔx=RO/XO・ΔX (or Δr=a
The relationship is Δθ=RO/θ0·Δθ).

Therefore, for example, if the target resistance value RO is 5000
Ω, the angle formed by both electrodes (= maximum rotation angle of the moving electrode) θ
When manufacturing a rotary potentiometer where 0 is 351°, a=Ro/θ0=5000Ω/351°=1
4.2Ω10. Now, the reference unit interval is Δθ=2
If trimming is performed by selecting the reference unit resistance value Δr=aΔθ=RO/θ0 ・Δθ= 14.2
Ω/”X2′=28.4Ω.

After forming the reference cut 24a in this way, next, the unit distance ΔX (Δθ) is set from the tip of the reference cut 24a in the extending direction toward the other electrode 22 in parallel to the straight line that determines the inter-electrode distance. A correction notch 24b is formed that extends to a position separated by the same amount.

Next, the movable electrode 26 is moved to measure the resistance value R1 from the reference line S to the tip of the correction notch 24b, and the difference Δri between this measured resistance value R1 and the reference unit resistance value Δr is determined.

Next, this difference value Δr11 is compared with the reference unit resistance value Δr, an extension direction is determined based on the comparison result, and the correction notch 24b is further extended by a unit distance ΔX from the tip of the correction notch. do.

That is, as a result of the comparison, if the difference value Δr11 is below a certain range, the correction notch 24a is extended in the same direction (direction indicated by arrow F in FIG. 3), and this difference is The value Δr11 is the reference unit resistance value Δr
If the resistance value of the resistive film 23 is larger than Δr by a certain value or more, the resistance value of the resistive film 23 is extended in the direction shown by the arrow U in FIG. If the resistance value of the resistance film 23 is small, it is extended in the direction of increasing the resistance value of the resistance film 23 (the direction indicated by the arrow in FIG. 3).

For example, in the case of the above-mentioned rotary potentiometer, the value in the certain range is set to the reference unit resistance value Δr (=28
．． 4Ω), the value of the difference Δr1 and the direction of extension are as follows.

When 28.7Ω≧8r11≧28.1Ω, F direction Δr1
When 1<28.1Ω, the D direction When Δr11>28.7Ω, the U direction and below. By repeating this procedure one after another until reaching the vicinity of the other electrode 22, the desired linearity and predetermined linearity can be achieved. A resistive film having a resistance value (5000Ω) can be obtained. Note that, if necessary, after a predetermined resistance value is reached, the correction notch is extended to one edge of the resistor j pattern to completely form the portion to be removed into an island shape.

Note that the apparatus for executing the procedure in the above-mentioned practical example includes, for example, a processing laser device β for forming the notch 24, a resistance value measuring device for measuring each of the resistance values,
A movable stage that supports the resistive film 23 and can accurately align the laser beam of the processing laser device to a desired position on the resistive film 23, a drive device that drives the stage, and these laser devices; Examples include a device equipped with a control device that controls a resistance ffi measuring device, a stage driving device, etc., or has a built-in microcomputer or the like into which a program is input to perform certain arithmetic processing and carry out the above steps. .

FIG. 4 is a graph showing an example of the results obtained when the present inventors fabricated an apparatus for carrying out the method of the second embodiment and actually attempted to trim the tantalum nitride resistive film of the rotary potentiometer.

In other words, in Fig. 4, the vertical axis represents the deviation width of the resistance value of the resistive film actually obtained with respect to the target resistance straight line (R = aθ) (the target resistance value at each position is approximated by the least squares method). The horizontal axis represents the position of the resistive film between the electrodes as an angle (θdeg
).

For comparison, FIG. 5 shows the results when the same resistive film as in the second embodiment was trimmed by the conventional trimming method using a drill, similar to the graph in FIG. 4. This is shown in .

As is clear from the above results, both have almost the same precision in terms of resistance linearity.

However, the time required for trimming was approximately 15 minutes in the case of the conventional example shown in FIG. 5, whereas in the present example shown in FIG.
By using a laser device with high repetition rate irradiation of Hz, it was possible to carry out the process in about 4 minutes and 30 seconds.

Furthermore, in the conventional example, a large amount of cutting waste was generated during trimming, whereas in this example, hardly any dust-like dust could be observed.

[Effects of the Invention] As described in detail above, the present invention does not remove the entire region of the resistive film to be removed, but removes at least part of the chain line along the line surrounding the region of the resistive film to be removed. A notch is formed in the resistive film over a section of This makes it possible to obtain the same effect as when all the areas to be removed are removed, thereby making it possible to significantly shorten the trimming time and suppress the generation of dust and the like.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a method for trimming a resistive film according to a first embodiment of the present invention, and FIGS. 2 and 3 are diagrams for explaining a method for trimming a resistive film according to a second embodiment of the present invention. FIG. 4 is a graph showing an example of the results of actually attempting to trim the resistive film of the rotary potentiometer by the inventors of the present invention by fabricating an apparatus for carrying out the method of the second embodiment. For comparison, the figure is a graph showing the results of trimming a resistive film similar to that of the second embodiment using a conventional trimming method using a drill, similar to the graph of FIG. 4, and FIG. 8 to 8 are diagrams showing conventional examples of the present invention. 11.12, 21.22... electrode, 13.23...
Resistive film, 14. 24... Notch, 24a... Reference notch, 14b, 24b... Correction notch, 15
．． 25... Correction notch, 26... Moving electrode, Δ
X...Unit distance leakage.

Claims (2)

[Claims] (1) A resistive film trimming method in which the resistance value between the electrodes is corrected by removing a part of the resistive film formed between the electrodes, in which the resistive film is trimmed along a line surrounding the area to be removed of the resistive film. A cut is formed in the resistive film over at least a part of the line, and the region to be removed, which contributed to conduction between the electrodes before the cut was formed, is removed from the region after the cut is formed. A method for trimming a resistive film, comprising modifying the resistance value between the electrodes so that it no longer contributes to conduction. (2) A resistive film trimming method in which the resistance value between the electrodes is corrected by removing a part of the resistive film formed between the electrodes, wherein a unit section serving as a reference is provided in the resistive film, and the unit section is from one edge of the two edges of the resistive film other than the edge connected to the electrode toward the center of the resistive film so that the resistance value becomes a reference unit resistance value, A reference cut is provided in which a region spanning the section is removed, and then a reference cut is provided from the tip of the reference cut toward one of the electrodes to a position separated by a unit distance equal to the section distance of the unit section. providing a correction cut to be extended; then comparing the resistance value of the section of the resistive film in which the correction cut is formed with the reference unit resistance value; and then determining the direction of extension based on the comparison result. The correction notch is further extended by a unit distance from the tip of the correction notch, and the resistance value of the section where the correction notch is provided is compared with the reference unit resistance value in the same manner as above. A method for trimming a resistive film, characterized in that the resistance value of the resistive film is corrected by successively repeating the steps of determining the extension direction and providing correction incisions based on the results.