JPH06347501A - Method and apparatus for inspecting surface acoustic wave type band-pass filter - Google Patents

Abstract

PURPOSE:To surely detect a short circuit defect before assembly. CONSTITUTION:An electric signal is applied between a comb shaped input electrode and a comb shaped ground electrode via a coaxial probe P1, ground probes G1, G2 and a pad from an output terminal 61 of a frequency analyzer 60. An electric signal generated between a comb shaped output electrode and the comb shaped ground electrode is supplied to an input terminal 62 of the frequency analyzer 60 via the pad, a coaxial probe P2 and ground probes G3, G4, then a passing rate in a range of prescribed frequencies near the central frequency thereof in a passing band of a surface acoustic wave type band-pass filter is measured so that, when the passing rate becomes equal to or lower than a prescribed value, it is judged that there is a defect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection method and apparatus for mainly detecting a short circuit defect before packaging a surface acoustic wave (SAW) type bandpass filter which is a chip component.

[0002]

2. Description of the Related Art A surface acoustic wave type bandpass filter as shown in FIG. 7 is used in an automobile telephone, a mobile telephone and the like. This filter is a chip component, and the chip 10
Has a structure in which a metal film such as aluminum is deposited on a piezoelectric substrate 11, for example, a LiTaO3 substrate by sputtering or the like, and an electrode pattern is formed by photoetching. In FIG. 7, the number of electrodes is smaller than it actually is.

The comb-shaped ground electrode 20 includes comb-shaped electrodes 21 to 21.
25 are alternately arranged in the opposite direction. Pads GND0 to GND4 are connected to the comb electrodes 23, 22, 24, 21 and 25, respectively, via wiring. The comb-shaped input electrode 30 is formed so as to mesh with the comb-shaped electrode 23, and is connected to the pad IN via a wiring. The comb-shaped output electrode 40 is formed so that the comb-shaped electrodes 41 and 42 mesh with the comb-shaped electrodes 22 and 24, respectively, and is connected to the pad OUT via a wiring. Comb-shaped reflective electrode 5
1 and 52 are formed so as to mesh with the comb electrodes 21 and 25, respectively, to reduce energy loss.

Pads IN, OUT and GND0 to GND
4 is connected to an external terminal (not shown) by a wire bonder. In the above structure, when a high-frequency signal is input between the comb-shaped input electrode 30 and the comb-shaped ground electrode 20, this electric signal is converted into a surface acoustic wave by the inverse piezoelectric effect, and then the comb-shaped ground electrode 20 by the piezoelectric effect. Comb-shaped output electrode 4
It is converted into an electric signal between 0 and 0.

In FIG. 7, the electrode has a one-stage structure, but in order to sufficiently increase the attenuation rate of the suppression band on both sides of the pass band, as shown in FIG. A filter is used. 8, the same or similar components as those in FIG. 7 are designated by the same or similar reference numerals as those in FIG. 7. In FIG. 8, the number of electrodes is smaller than it actually is.

The comb-shaped ground electrode 20A is formed by a series of comb-shaped electrodes 21A to 23A facing in the same direction and connected to the pads GND1, GND2 and GND01, GND02. The comb-shaped input electrode 30 includes the comb-shaped electrode 3
1, 32, and 33 are formed so as to mesh with the comb electrodes 21A, 22A, and 23A, respectively, and are connected to the pad IN together. The output side is symmetrical with the input side. That is, in the comb-shaped ground electrode 20B, comb-shaped electrodes 21B to 23B facing in the same direction are connected,
Pads GND3, GND4 and GND03, GND04
It is connected to the. In the comb-shaped output electrode 40, the comb-shaped electrodes 41, 42 and 43 are respectively comb-shaped electrodes 21B and 22B.
And 23B are formed so as to mesh with each other, and the pads OU are formed together.
It is connected to T.

A comb-shaped floating electrode 20C in which comb-shaped electrodes 21C to 24C are connected is formed between the comb-shaped ground electrode 20A and the comb-shaped ground electrode 20B, and the pad F is formed.
It is connected to L1 and FL2. Comb-shaped electrodes 21C to 2
Parallel connection electrodes 51 to 54 are formed inside the 4C so as to mesh with them. Pad IN, O
The UT and GND0 to GND4 are connected to an external terminal (not shown) by a wire bonder.

In FIGS. 7 and 8, the electrodes other than the pads are shown by solid lines for simplification.
The width of each electrode and the width between electrodes are 1μ in the 00MHZ band.
Since it is about m, the electrodes may be broken or the electrodes may be short-circuited in the patterning process. Therefore,
Conventionally, a continuity test is performed after wafer dicing. That is, a short circuit is detected by bringing the probe into contact with the pads IN, OUT and GND1 to 4 on the chip and measuring the resistance value between the probes.

[0009]

However, it is not possible to connect a pad to each of the comb-shaped reflective electrodes 51 to 54 in FIG. 8, so that a short circuit between them and the comb-shaped electrodes 21C to 24C is caused. Cannot be detected. The influence of the disconnection of the electrodes on the filter characteristics is relatively small, and the quality of the filter depends on the degree of the disconnection. However, the short circuit between the electrodes has a great influence on the filter characteristics at any part, resulting in a defective product. Therefore, the yield is lowered in the test after assembling, and useless packages and caps are used, resulting in high cost.

In view of the above problems, an object of the present invention is to provide a surface acoustic wave type bandpass filter inspection method and apparatus capable of surely detecting a short circuit failure in a stage before assembly.

[0011]

A surface acoustic wave bandpass filter inspection method and apparatus according to the present invention will be described with reference to the reference numerals of corresponding constituent elements in the drawings of the embodiments. According to the present invention, for example, as shown in FIGS. 1, 5 and 8, a pattern of a metal electrode film is formed on a piezoelectric substrate 11A, and the comb-shaped input electrode 30 and the comb-shaped ground electrode 20A mesh with each other. , Comb-shaped output electrode 40
And the comb-shaped ground electrode 20B mesh with each other to form the comb-shaped input electrode 30, the comb-shaped output electrode 40, and the comb-shaped ground electrode 2.
Pads IN, OUT, GND1 to GND on 0A and 20B
In a surface acoustic wave bandpass filter inspection device for detecting a short circuit defect between electrodes for a chip-type surface acoustic wave bandpass filter before packaging in which 4 are connected, the output terminal 61 Passage rate T of the electric signal input to the input terminal 62 with respect to the output electric signal
Is substantially measured in a set frequency range f _{1 to} f ₂ near the center frequency within the pass band of the surface acoustic wave bandpass filter, the detecting means 70, and the detecting means 70 with respect to the chip. The moving means 75 and 76 for relatively moving and the moving means 75 and 76 are driven so that the tips of the first coaxial probe P1, the second coaxial probe P2 and the ground probes G1 to G4 respectively correspond to the corresponding pads I.
N, OUT, GND1 to GND4 are brought into contact with each other, the frequency analyzer 60 is operated in this state, and the first coaxial probe P
1, second coaxial probe P2 and ground probe G1
Connect the tip of G4 to pads IN, OUT, GND1 to GND4
Control means 80 for repeatedly executing the process of separating from
And pass / fail determination means 81 to 83 that determine a defect when the pass rate T becomes equal to or less than a set value T ₀ . In addition, the detection means 70 uses the output terminal 61 via the first coaxial cable S1.
Connected to the first connector C1, a first coaxial probe P1 having one end connected to the first connector C1 and an internal conductor wire exposed at the other end, and a second coaxial cable S2 connected to the input terminal 62. A second connector C2, a second coaxial probe P2 whose one end is connected to the second connector C2 and whose inner conductor is exposed at the other end, and a first coaxial probe P1 via the first connector C1 and the second connector C2. Ground probe G1 connected to the coated conductor of the second coaxial probe P2
To G4, the tip ends of the first coaxial probe P1, the second coaxial probe P2, and the ground probes G1 to G4 are connected to the comb-shaped input electrode 30, the comb-shaped output electrode 40, and the comb-shaped ground electrodes 20A and 20B, respectively. ,
It corresponds to OUT and GND1 to GND4.

According to the method of the present invention, an electric signal is output from the output terminal 61 of the frequency analyzer 60 to the probe and the pads IN and GN.
An electric signal applied between the comb-shaped input electrode 30 and the comb-shaped ground electrode 20A via D1 and GND2 and generated between the comb-shaped output electrode 40 and the comb-shaped ground electrode 20B is supplied to the pad O.
UT, GND3, GND4 and then supplied to the input terminal 62 of the frequency analyzer 60 via the probe, passing rate in the set frequency range f ₁ ~f ₂ around the center frequency of the pass band of the surface acoustic wave bandpass filter T Is substantially measured, and when the passing rate T becomes equal to or less than the set value T ₀ , it is determined to be defective.

The surface acoustic wave bandpass filter to be inspected is not limited to the one having a two-stage structure as shown in FIG. 8, and the one-stage structure as shown in FIG.
The structure may be more than a step. In addition, the above-mentioned "substantially measuring the passage rate" means, for example, measuring the attenuation rate. According to the present invention, a short circuit defect between arbitrary electrodes, for example, a defect due to a short circuit between the comb-shaped reflective electrodes 51 to 54 and the comb-shaped electrodes 21C to 24C, which cannot be connected to the pads, is surely made at a stage before assembly. Can be detected.

Furthermore, it is possible to use the inspection method and apparatus having the same structure regardless of the number of electrode steps of the surface acoustic wave bandpass filter. In addition, the chips judged to be defective are
It can be excluded from the subject of die bonding, whereby waste of the package and cap can be omitted, wasteful assembly work for defective chips can be omitted, and the yield of tests after assembly can be improved and cost can be reduced.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall configuration of a surface acoustic wave bandpass filter inspection apparatus. The frequency analyzer 60 has a coaxial cable S1 at an output terminal 61 and an input terminal 62 thereof, respectively.
, And one ends of S2 are connected. The other ends of the coaxial cables S1 and S2 are connected to the connectors C1 and C2 of the detection unit 70, respectively.

As shown in FIG. 2, connectors C1 and C2 are also provided.
Are connected to one ends of coaxial probes P1 and P2, respectively, and internal conductors are exposed at the tips of the coaxial probes P1 and P2. The coated conductors of the coaxial probes P1 and P2 are connected to the ground loop G via the connectors C1 and C2.
It is connected to 0. One end of the ground probes G1 to G4 is connected to the ground loop G0. The tips of the coaxial probes P1 and P2 and the ground probes G1 to G4 are the pads IN, OUT, and GND on the chip 10A.
It corresponds to 1 to GND4.

The detecting section 70 can actually be constructed as shown in FIG. In this detection unit 70, a circular hole 72 is formed in the central portion of a substrate 71, and the substrate 71 around the circular hole 72 is formed.
The ground loop G0 is printed on the upper side, and the connectors C1 and C2 are attached to the holes formed at the opposite positions on the ground loop G0. In FIG. 3, the coaxial probes P1 and P2 and the ground probes G1 to G4 are
The tip portion thereof faces upward on the paper surface (the direction in which the sample exists).

An edge sensor 73 is attached to the ground probe G1. This edge sensor 73 is
It is a switch that is turned on when there is no contact (to determine an edge sensor failure when it is off without contact) and turned off when it comes into contact, and in the figure, the wiring along the ground probe G1 for the edge sensor 73 is shown. Omitted. The edge sensor 73 comes into contact with the ground pad on the sample slightly before the tip of the ground probe G1 comes into contact with the ground pad, and operates to detect this.

In FIG. 1, a marker 74 for marking a defective chip is arranged on the side of the detection section 70. The detection unit 70 and the marker 74 are fixed to a Z stage 76 arranged above the XY stage 75 and capable of being driven in the direction perpendicular to the paper surface. On the other hand, the sample W is obtained by performing dicing in a state where the wafer is adhered to the dicing tape and separating the individual chips, and is mounted on the XY stage 75.

The detection signal of the edge sensor 73 and X
-The position signals of the Y stage 75 and the Z stage 76 are controlled
Supplied to the control device 80, the marker 74, the XY stage
75 and Z stage 76 are controlled by the controller 80.
Be done. The controller 80 uses a microcomputer
It is configured. Here, the keyboard of the frequency analyzer 60
Operate the switch 63 to adjust the frequency range and
Set the number of measurement points and put the detector 70 in the contact state shown in FIG.
Then, when the frequency analyzer 60 is operated, the frequency analyzer 6
0 monitor display 64, as shown in FIG.
A graph of pass characteristics is obtained. This pass characteristic is
If there is no short circuit between the electrodes on 10A, then FIG.
As shown in (A), but if there is a short circuit, short
Frequency f near the center of the pass band regardless of the position₁~ F ₂
The present inventors have found that attenuation appears in the range of.

Therefore, the keyboard 63 is set to operate so as to measure, for example, 10 points in the range of the frequencies f _{1 to} f ₂ . In addition, in FIG. 5, the characteristic impedance is 50Ω.
The coaxial cables S1 and S2 and the probe of No. 1 are actually measured under the condition that impedance matching is not achieved between the test object having a characteristic impedance of about 50Ω. Tests have shown that this is for the purpose and that for this purpose it is not necessary to connect an impedance matching circuit between the probe and the test object.

The sample W contains one calibration / alignment chip 10B as shown in FIG. In this calibration / alignment chip 10B, a short circuit line 90 is formed on a piezoelectric substrate 11B, and pads IN and O are provided at both ends thereof.
The UT is formed and is formed in the same step as the chip 10A. For each sample W, or at least for each lot of sample W, the tips of the coaxial probes P1 and P2 of the detection unit 70 are brought into contact with the pads IN and OUT, respectively, and in this state,
Frequency f1 ~f passing rate T ₂ ranges calibrated so that the 0 dB.

An alignment mark 91 for aligning the mask attached to the exposure apparatus with respect to the wafer is also formed on the piezoelectric substrate 11B to reduce the use of extra chips. Frequency analyzer 60
Responds to the measurement start signal ST from the control device 80, measures the pass rate T within the set range, and supplies this to the comparator 81 together with the output enable signal. The comparator 81 compares the passing rate T with the reference value T ₀ set by the reference value setting unit 82, and if T ≦ T ₀ and the output enable signal is active, sets the output to a high level.
The output of the comparator 81 is held in the RS flip-flop 83 and supplied to the control device 80. The RS flip-flop 83 is reset by the measurement start signal ST.

Next, the chip inspection procedure by the controller 80 will be described with reference to FIG. Hereinafter, the numerical value in the parentheses is the step identification number in the figure. (100) Perform the same processing as the following steps 101 to 104 to bring the tips of the coaxial probes P1 and P2 into contact with the pads IN and OUT shown in FIG. 4, respectively. By supplying the calibration signal CR to the frequency analyzer 60,
As described above, the pass rate is 0 in the set frequency range f _{1 to} f _2.
Automatically calibrate to dB.

(101) The XY stage 75 is driven to position the first or next chip 10A to be inspected under the probe of the detector 70. (102, 103) until the edge sensor 73 operates,
The Z stage 76 is driven downward at high speed. (104) The Z stage 76 is moved further downward at a low speed for a set distance to bring it into the contact state shown in FIG.

(105) The measurement start signal ST is supplied to the reset input terminal R of the RS flip-flop 83 and the frequency analyzer 60. As a result, the pass rate T of the set number of points within the set frequency range is output from the frequency analyzer 60. When (106, 107) T ≦ T ₀ , the controller 80
Moves the XY stage 75 one chip to the right in FIG. 1, marks the center of the chip 10A with the tip of the marker 74, and moves the XY stage 75 to the left and right in FIG.
Moves by the amount of chips and returns.

The chip with this mark is later detected by the die bonder and excluded from the subject of die bonding.
As a result, waste of packages and caps can be eliminated, wasteful assembly work for defective chips can be omitted, and the yield of tests after assembly can be improved and cost can be reduced. (108) If there is an uninspected chip 10A, the process returns to step 101 and the above process is repeated.

The present embodiment is not limited to the two-stage surface acoustic wave bandpass filter shown in FIG. 8, but also the one-stage configuration shown in FIG. 7 or a surface acoustic wave type bandpass having three or more stages not shown. For the inspection of the filter, the inspection device having the same configuration can be used regardless of the number of stages. Moreover, it is possible to detect a defect due to a short circuit between the comb-shaped reflective electrodes 51 to 54 and the comb-shaped electrodes 21C to 24C shown in FIG.

[0029]

As described above, according to the present invention, there is provided a surface acoustic wave bandpass filter inspection method and apparatus for detecting a short circuit between electrodes of a chip type surface acoustic wave bandpass filter before packaging. , An electric signal from the output terminal of the frequency analyzer is applied between the comb-shaped input electrode and the comb-shaped ground electrode via the probe and the pad, and the electric signal generated between the comb-shaped output electrode and the comb-shaped ground electrode is
It is supplied to the input terminal of the frequency analyzer through the pad and probe, and the pass rate in the set frequency range near the center frequency in the pass band of the surface acoustic wave bandpass filter is substantially measured. When it becomes the following, it is determined to be defective, so that the following excellent effects are achieved.

(1) Short circuit failure between arbitrary electrodes, for example,
A defect due to a short circuit between the electrode to which the pad cannot be connected and another electrode can be reliably detected in the stage before assembly. (2) The inspection method and apparatus having the same configuration can be used regardless of the number of electrode steps of the surface acoustic wave bandpass filter.

(3) Chips determined to be defective can be excluded from die bonding, which eliminates waste of packages and caps and eliminates unnecessary assembly work for defective chips. It is possible to improve the yield of the test and reduce the cost.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a surface acoustic wave type bandpass filter inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a connection diagram of a detection unit.

FIG. 3 is a plan view showing a configuration of a detection unit.

FIG. 4 is a plan view of a calibration / alignment chip.

FIG. 5 is a pass characteristic diagram of a bandpass filter.

FIG. 6 is a flowchart showing a chip inspection procedure of a surface acoustic wave bandpass filter.

FIG. 7 is a configuration diagram of a surface acoustic wave type bandpass filter having one stage of electrodes.

FIG. 8 is a configuration diagram of a surface acoustic wave type bandpass filter having two electrodes.

[Explanation of symbols]

10, 10A, 10B chip 10B calibration / alignment chip 11, 11A, 11B piezoelectric substrate 20 comb-shaped ground electrode 30 comb-shaped input electrode 40 comb-shaped output electrode 51-54 comb-shaped reflective electrode 60 frequency analyzer 70 detector 71 Substrate 75 XY stage 76 Z stage 80 Control device 81 Comparator 82 Reference value setter 83 RS flip-flop IN, OUT, GND0 to GND4, GND01 to GND
D04, FL1, FL2 Pad C1, C2 Connector S1, S2 Coaxial cable P1, P2 Coaxial probe G0 Ground loop G1-G4 Ground probe

Claims (2)

[Claims] 1. A pattern of a metal electrode film is formed on a piezoelectric substrate (11A), and the pattern has a comb-shaped input electrode (3).
0) and the comb-shaped ground electrode (20A) mesh with each other, and the comb-shaped output electrode (40) and the comb-shaped ground electrode (20)
B) meshes with each other, and pads (IN, OUT,) are formed on the comb-shaped input electrode, the comb-shaped output electrode, and the comb-shaped ground electrode.
A surface acoustic wave bandpass filter inspection method for detecting a short-circuit defect between electrodes is applied to a chip type surface acoustic wave bandpass filter before packaging, which has a shape in which GND1 to GND4) are connected. An electric signal from the output terminal (61) of the analyzer (60) is applied between the comb-shaped input electrode and the comb-shaped ground electrode via the probe and the pad, and is generated between the comb-shaped output electrode and the comb-shaped ground electrode. The supplied electric signal is supplied to the input terminal (62) of the frequency analyzer through the pad and the probe, and the set frequency range (f ₁ to f ₁ to near the center frequency in the pass band of the surface acoustic wave bandpass filter is supplied. The surface acoustic wave type bandpass filter is characterized in that the pass rate at f ₂ ) is substantially measured, and it is determined to be defective when the pass rate becomes equal to or less than a set value (T ₀ ). Inspection method. 2. A pattern of a metal electrode film is formed on a piezoelectric substrate (11A), and the pattern has a comb-shaped input electrode (3).
0) and the comb-shaped ground electrode (20A) mesh with each other, and the comb-shaped output electrode (40) and the comb-shaped ground electrode (20)
B) meshes with each other, and pads (IN, OUT,) are formed on the comb-shaped input electrode, the comb-shaped output electrode, and the comb-shaped ground electrode.
In a surface acoustic wave type band pass filter inspection device for detecting a short circuit defect between electrodes, for a chip type surface acoustic wave type band pass filter before packaging, which has a shape in which GND1 to GND4) are connected, The pass ratio of the electric signal input to the input terminal (62) with respect to the electric signal output from the terminal (61) is set to a set frequency range (f _{1 to} f) near the center frequency in the pass band of the surface acoustic wave bandpass filter. ₂ ) a frequency analyzer (60) for substantially measuring, a first connector (C1) connected to the output terminal via a first coaxial cable (S1), and one end connected to the first connector and the other end A first coaxial probe (P1) whose internal conductor is exposed, a second connector (C2) connected to the input terminal through a second coaxial cable (S2), and one end of the second coaxial probe (P2). The inner conductor of the other end is connected to Kuta is exposed 2
Coaxial probe (P2) and ground probes (G1 to G4) connected to the coated conductors of the first coaxial probe and the second coaxial probe through the first connector and the second connector
And detecting means in which the tip positions of the first coaxial probe, the second coaxial probe, and the ground probe correspond to the comb-shaped input electrode, the comb-shaped output electrode, and the pad connected to the comb-shaped ground electrode, respectively. (70), moving means (75, 76) for moving the detecting means relative to the chip, and driving the moving means to move the first coaxial probe, the second coaxial probe and the ground probe. Control for repeatedly executing a process of bringing the tips into contact with the corresponding pads, operating the frequency analyzer in this state, and separating the tips of the first coaxial probe, the second coaxial probe, and the ground probe from the pads A table (80), and a pass / fail judgment means (81-83) for judging a failure when the passing rate becomes equal to or lower than a set value (T ₀ ). Surface acoustic wave bandpass filter inspection system.