JP2004151035A - Inspection method and device of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve determination accuracy in an inspection device 21 for determining an oscillation defective article of a pickup element 1 for an optical disc having a high gain and a wide band. <P>SOLUTION: An output load capacity C2 (C1≪C2) is provided in an output load circuit 22 together with an output load capacity C1 specified by a specification of the element 1 and set so as to be equivalent to a mounted substrate capacity to which an output terminal is connected, an input resistance of a subsequent circuit or the like, relative to the pickup element 1 for the optical disc constituted by being equipped with a transimpedance type amplifier having a high gain and a high band and a constant-current output type output buffer circuit, and a measuring device 23 determines oscillation from the difference of output voltages acquired by switching the output load capacities by a change-over switch SW. Consequently, even when an output falls in a range of a proper output value by the capacity C1 specified by the specification, a balance of charge/discharge is disordered and the value comes to fall out of the range of the proper output value by switching to the capacity C2, to thereby enable to determine highly accurately the oscillation defective article. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inspection method and apparatus for determining the presence or absence of oscillation of a semiconductor device including a constant-current output type output circuit in a pre-stage circuit having a gain, such as a wide-band amplifier.
[0002]
[Prior art]
FIG. 4 is a block diagram showing an electrical configuration of the optical disk pickup element 1 which is the semiconductor device as described above. The optical disk pickup device 1 is a device that receives an optical signal from a photodiode PD and amplifies the signal. The optical disk pickup device 1 is generally provided with the photodiode PD, a transimpedance amplifier 2 including a feedback resistor Rf, and an output buffer circuit 3.
[0003]
As shown in FIGS. 5 and 6, the output buffer circuit 3 includes a series circuit of a transistor Tr and a constant current source F connected between power supply lines, and a connection between an emitter of the transistor Tr and a constant current source F. An emitter-follower buffer configured so that a point becomes an output terminal. A signal amplified by the transimpedance amplifier 2 as a preceding circuit is input to the base of the transistor Tr, and the emitter is output. This output buffer circuit 3 is of a constant current output type as described above, and can be applied to a wider range of circuit characteristics and circuit scales required than a push-pull amplifier, and has a wide output voltage range. It has a great advantage.
[0004]
In addition, although the transimpedance amplifier 2 is provided as an example of the amplifier 2 because it includes a light receiving element, the present invention is not limited to this transimpedance amplifier.
[0005]
The optical disc pickup element 1 configured as described above becomes unstable due to the problem of likelihood (characteristics) of the constituent elements as the speed and the bandwidth are increased, and the pickup element 1 oscillates due to an increase in noise due to the bandwidth. It's easier. Therefore, for example, the presence or absence of oscillation is determined by the inspection apparatus 11 shown in Japanese Patent Application Laid-Open No. 7-218598 or FIG. The inspection device 11 includes an output load circuit 12 having a value specified at the output terminal of the optical disk pickup element 1 and a measurement device 13 which connects the output load circuit 12 and determines whether or not oscillation occurs. It is composed. The output load circuit 12 comprises a parallel circuit of a resistor r and an output load capacitance c.
[0006]
In the optical disc pickup device 1, the amplified signal is input to the subsequent IC through the flexible substrate or the like, so that the wiring capacitance of the flexible substrate or the like exists as the output load capacitance c between the output terminal and GND. The input resistance of the IC becomes the load resistance r, and the resistance value of the resistance r and the capacitance value of the output load capacitance c are set in the output load circuit 12 so as to be equivalent to those values.
[0007]
Then, the output load circuit 12 is connected, the voltage Vo of the output terminal is measured, and an element which is out of a reference value range of an appropriate output value specified in advance is selected by a measuring device 13 such as a wafer test. As a result, outflow of defective oscillation products and the like is prevented. No light enters the photodiode PD during the oscillation inspection, that is, no current flows through the photodiode PD, and the input is equivalent to an open state. Along with this oscillation inspection, other characteristics (including operation confirmation at the time of light input) are also inspected under each load condition corresponding to the specification setting condition.
[0008]
[Patent Document]
JP-A-7-218598 (publication date: August 18, 1995)
[0009]
[Problems to be solved by the invention]
However, in the prior art as described above, when an oscillation failure occurs, if the output voltage Vo has an oscillation waveform as shown in FIG. 8, the output voltage Vave1 sampled by the measuring device 13 is equal to the appropriate output value. A sufficient output difference occurs in the reference value range and can be detected by a characteristic test. However, when the oscillation waveform is as shown in FIG. 9, the output voltage Vave2 sampled by the measuring device 13 is equal to the reference value. Since there is no difference between the value ranges and no reproducibility, there is a problem that it is impossible to completely sort by a characteristic inspection.
[0010]
More specifically, the output waveform is smoothed in the output load capacitance c and the measuring device 13. At this time, if the charging and discharging of the output load capacitance c by the constant current output type output buffer 3 are balanced (sinusoidal waveform) by the values of the output load capacitance c and the resistance r according to the specification setting conditions, The output voltages Vave1 and Vave2 sampled in the measuring device 13 are the center values of the oscillation waveform. If the center value falls outside the reference value range as shown by the output voltage Vave1 in FIG. 8 due to an offset between the optical disk pickup element 1 as the circuit to be inspected and the measuring device 13, etc., oscillation occurs. However, if the output voltage Vave2 falls within the reference value range as shown by the output voltage Vave2 in FIG. 9, the output becomes the same as that of a non-defective product shown in FIG. 10 in which oscillation does not occur, and it cannot be determined that oscillation occurs.
[0011]
For this reason, in order to reliably remove defective products with oscillation, it was necessary to perform a great deal of time and cost, such as performing an all-output check on all the products using an oscilloscope.
[0012]
An object of the present invention is to provide a method and an apparatus for inspecting a semiconductor device, which can improve the accuracy of determining a defective oscillation product.
[0013]
[Means for Solving the Problems]
An inspection method of a semiconductor device according to the present invention comprises: a semiconductor device including a pre-stage circuit having a gain; and a constant current output type output circuit that receives a current from the pre-stage circuit. In the inspection method for determining presence / absence, a plurality of output load capacitors are selectively connected to an output terminal.
[0014]
According to the above configuration, a semiconductor device including a pre-stage circuit having a gain, such as a transimpedance amplifier, and a constant-current output type output circuit that receives a current from the pre-stage circuit as an input. Inspection of the semiconductor device, particularly oscillation, is performed by connecting an output load defined in the specifications of the semiconductor device and set so as to be equivalent to a mounting substrate capacitance to which an output terminal is connected, an input resistance of a subsequent circuit, and the like. In determining the presence / absence of the output load, a plurality of output load capacitances in the output load are provided and selectively connected, and the presence / absence of the oscillation is determined from each of the switched outputs. The selection of the output load capacitance may be performed by, for example, providing a plurality of capacitors having mutually different capacitance values and connecting them alternately. It may be performed by switching the number of connections or the number of series connections.
[0015]
Therefore, when a defective oscillator is determined when the amplitude of the output signal exceeds the range of the proper output value, the center value of oscillation is limited to the range of the proper output value with a single type of output load specified in the above specification. Only when there is a large offset from the output load capacity or the output smoothed by the inspection device is out of the range of the appropriate output value, it is possible to determine a defective oscillation product. If the output falls within the range of the appropriate output value, it is not possible to judge a defective oscillation product. On the other hand, by switching the output load capacity, the constant current output type output circuit does not satisfy the output load capacity. It is highly possible that the smoothed output is out of the range of the appropriate output value because the balance of the discharge is lost, and it is possible to determine that the oscillation is defective. As a result, the accuracy of determining a defective oscillation product can be improved.
[0016]
Further, the method for testing a semiconductor device according to the present invention is characterized in that the presence or absence of oscillation is determined from an output difference due to the switching of the output load capacitance.
[0017]
According to the above configuration, even if there is an offset between the semiconductor device and the measuring device, the offset is removed by calculating the output difference as a result of switching the output load capacitance, and the determination accuracy of the oscillation defective product is determined. Can be further increased.
[0018]
Still further, in the semiconductor device inspection method of the present invention, the output load capacitance is switched a plurality of times, an average value of outputs at each output load capacitance is obtained, and the presence or absence of oscillation is determined from a difference between the average values. It is characterized by doing.
[0019]
According to the above configuration, the determination accuracy can be further improved.
[0020]
In addition, the semiconductor device inspection apparatus of the present invention is a semiconductor device configured to include a pre-stage circuit having a gain and a constant current output type output circuit that receives a current from the pre-stage circuit. In the inspection device for determining the presence or absence of oscillation, a plurality of output load capacitances, switching means for selectively connecting the output load capacitance to an output terminal of the semiconductor device, and an output based on the output load capacitance switched by the switching means. And a determination means for determining the presence or absence of the oscillation.
[0021]
According to the above configuration, a semiconductor device including a pre-stage circuit having a gain, such as a transimpedance amplifier, and a constant-current output type output circuit that receives a current from the pre-stage circuit as an input. Inspection of the semiconductor device, particularly oscillation, is performed by connecting an output load defined in the specifications of the semiconductor device and set so as to be equivalent to a mounting substrate capacitance to which an output terminal is connected, an input resistance of a subsequent circuit, and the like. In determining the presence or absence of the output load, a plurality of output load capacities in the output load are provided, and the connection is selectively performed by the switching means. The determination means determines the presence or absence of the oscillation from each of the switched and connected outputs. The selection of the output load capacitance may be performed by, for example, providing a plurality of capacitors having mutually different capacitance values and connecting them alternately. It may be performed by switching the number of connections or the number of series connections.
[0022]
Therefore, when a defective oscillator is determined when the amplitude of the output signal exceeds the range of the proper output value, the center value of oscillation is limited to the range of the proper output value with a single type of output load specified in the above specification. Only when there is a large offset from the output load capacity or the output smoothed by the inspection device is out of the range of the appropriate output value, it is possible to determine a defective oscillation product. If the output falls within the range of the appropriate output value, it is not possible to judge a defective oscillation product. On the other hand, by switching the output load capacity, the constant current output type output circuit does not satisfy the output load capacity. It is highly possible that the smoothed output is out of the range of the appropriate output value because the balance of the discharge is lost, and it is possible to determine that the oscillation is defective. As a result, the accuracy of determining a defective oscillation product can be improved.
[0023]
Still further, in the semiconductor device inspection apparatus according to the present invention, the determination unit determines the presence or absence of oscillation from an output difference caused by switching the output load capacitance.
[0024]
According to the above configuration, even if there is an offset between the semiconductor device and the measuring device, the offset is removed by calculating the output difference as a result of switching the output load capacitance, and the determination accuracy of the oscillation defective product is determined. Can be further increased.
[0025]
Further, in the semiconductor device inspection device of the present invention, the output load is formed of a parallel circuit of an output load capacitance and a resistor connected between the output terminal of the semiconductor device and a fixed potential, and the output load capacitance is equal to the output load capacitance. A first output load capacitance and a second output load capacitance are provided, and a switch constituting the switching means selectively connects the first output load capacitance and the second output load capacitance to the output terminal. It is characterized by doing.
[0026]
According to the above configuration, the switching of the output load capacity can be realized with a simple configuration.
[0027]
Furthermore, in the semiconductor device inspection device of the present invention, the first output load capacitance is set to a small capacitance value with respect to the oscillation frequency of the semiconductor device so that the output oscillation waveform of the output circuit is not distorted. The second output load capacitance is set to a large capacitance value such that the output oscillation waveform of the output circuit is distorted.
[0028]
According to the above configuration, the first output load capacitance C1 and the second output load capacitance C2 such that C1≪C2 are provided at the output terminal of the semiconductor device. The first output load capacitance C1 has such a small capacitance that the output oscillation waveform is not distorted (follows the input waveform) when the semiconductor device has an oscillation failure. At this time, when the resistance is indicated by R, the time constant t1 with respect to the signal frequency f1 of the preceding circuit is represented by C1 · R. The second output load capacitance C2 has a large capacitance value that causes the output oscillation waveform to be distorted (not to follow the input waveform but to be flattened). At this time, the time constant t2 is represented by C2 · R.
[0029]
Accordingly, the time constant C1 ・ R≪C2 ・ R is obtained from C1≪C2, and the presence or absence of oscillation can be more accurately determined based on the presence or absence of the difference between the outputs as described above.
[0030]
Further, in the semiconductor device inspection device of the present invention, the output circuit is configured such that a series circuit of a transistor Tr and a constant current source F is connected between power supply lines, and a connection point between the emitter of the transistor Tr and the constant current source F is provided. Is an emitter-follower type buffer configured to be the output terminal, and the second output load capacitor C2 does not cause waveform distortion at the unlimited output current value I1 via the transistor Tr, and The capacitance value is set so as to cause waveform distortion at the limited current value I2 through F.
[0031]
According to the above configuration, in the constant current output type output circuit, for example, the output load capacitance is charged with the unrestricted current value I1 and discharged with the restricted current value I2, and the output terminal has a small capacitance value. When the output load capacitance C1 is connected, the output voltage Vo1 has the ability of the output circuit to sufficiently charge and discharge the load capacitance.
| I1 · t / C1 | = | I2 · t / C1 | (where I2≪I1)
It becomes. Next, when an output load capacitor C2 having a large capacitance value is connected to the output terminal, the output voltage Vo2 has sufficient charging capability but has insufficient discharging capability with respect to the output load capacitor C2.
| I1 · t / C2 | ≫ | I2 · t / C2 | (where I2≪I1)
It becomes.
[0032]
Conversely, in a configuration in which the output load capacitance is discharged with the unrestricted current value I1 and charged with the restricted current value I2, when the output load capacitance C1 having a small capacitance value is connected to the output terminal, the output voltage Vo1 is output. Because the circuit has enough capacity to charge and discharge the load capacity,
| I1 · t / C1 | = | I2 · t / C1 | (where I2≪I1)
It becomes. Next, when an output load capacitor C2 having a large capacitance value is connected to the output terminal, the output voltage Vo2 has a sufficient discharge capability but a insufficient charge capability with respect to the output load capacitor C2.
| I1 · t / C2 | ≫ | I2 · t / C2 | (where I2≪I1)
It becomes.
[0033]
Therefore, by comparing the difference between the output voltages Vo1 and Vo2 for which the output load capacitance has been switched, the presence or absence of oscillation of the semiconductor device can be accurately determined.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention is described below with reference to FIGS. 1 to 3 and FIGS. 5, 6 and 8 to 10.
[0035]
FIG. 1 is a block diagram showing an electrical configuration of an inspection device 21 according to one embodiment of the present invention. The inspection device 21 determines whether or not the high-gain and wide-band optical disk pickup device 1 shown in FIG. 4 oscillates. The inspection device 21 includes an output load circuit 22 having a value specified at the output terminal of the optical disk pickup element 1 and a measurement device 23 connected to the output load circuit 22 to determine the presence or absence of oscillation. It is configured with.
[0036]
It should be noted that in the inspection device 21, the output load circuit 22 includes a resistor R, two output load capacitors C1 and C2, and a changeover switch SW for switching between the output load capacitors C1 and C2. That is being done. The output load capacitors C1 and C2 are integral loads that are selectively selected by the changeover switch SW and inserted between the output terminal of the optical disc pickup element 1 and GND in parallel with the resistor R.
[0037]
Here, in the present invention, C1 ≠ C2 and C1≪C2 are set. Further, in the optical disc pickup element 1, since the amplified signal is input to the subsequent IC through the flexible board or the like, the wiring capacity of the flexible board or the like is changed between the output terminal and GND by the output load defined in the above specification. It exists as a capacitance C1, and the input resistance of the latter-stage IC becomes a load resistance R. In the output load circuit 22, the resistance value of the resistance R and the capacitance value of the output load capacitance C1 are set to be equivalent to those values. Each is set.
[0038]
Then, the output load circuit 22 is connected, the output load capacitances C1 and C2 are switched, and the voltages Vo1 and Vo2 of the output terminals are measured. By selecting the elements that are out of the reference value range by the measuring device 23 such as a wafer test, the outflow of defective oscillation products and the like is prevented. No light enters the photodiode PD during the oscillation inspection, that is, no current flows through the photodiode PD, and the input is equivalent to an open state. Along with this oscillation inspection, other characteristics (including operation confirmation at the time of light input) are also inspected under each load condition corresponding to the specification setting condition.
[0039]
With this configuration, when determining an oscillation defective product when the output voltage Vo exceeds the reference value range of the appropriate output value, only a single type of output load capacitance C1 specified in the above-described specification is used. Only when the output voltage Vave1 smoothed as shown in FIG. 8 is greatly offset from the reference value range of the appropriate output value, the defective oscillation product can be determined. When the smoothed output voltage Vave2 falls within the reference value range, the oscillation defective product cannot be determined. On the other hand, by switching the output load capacitance to C2, the output load capacitance is switched to C2 as shown in FIG. 5 and FIG. In the constant current output type output buffer 3 as shown, the charge / discharge balance with respect to the output load capacitance C2 is lost, and the smoothed output voltage is Vave3, Vave of FIGS. As shown in, the higher the reference value range and can become the proper output value, it may be determined that an oscillation defective product. As a result, the accuracy of determining a defective oscillation product can be improved.
[0040]
Also, by determining the presence or absence of oscillation from the output difference ΔV = Vo2−Vo1 due to the switching between the output load capacitances C1 and C2, the offset between the optical disk pickup device 1 and the measuring device 23 as the device to be inspected is determined. Even if there is, the offset can be removed, and the accuracy of determining a defective oscillation product can be further improved.
[0041]
Hereinafter, a method of determining the presence or absence of oscillation from the output difference ΔV due to switching of the output load capacitances C1 and C2 will be described in detail with reference to FIGS. 5 and 6 and FIGS.
[0042]
As shown in FIGS. 5 and 6, the output buffer circuit 3 includes a series circuit of a transistor Tr and a constant current source F connected between power supply lines, and a connection between an emitter of the transistor Tr and a constant current source F. An emitter-follower buffer configured so that a point becomes an output terminal. A signal amplified by the transimpedance amplifier 2 as a preceding circuit is input to the base of the transistor Tr, and the emitter is output.
[0043]
In the output buffer circuit shown in FIG. 5, the transistor Tr is N-type, the collector is connected to the high-level power supply, the emitter is connected to the output terminal, and the low-level power supply is connected via the constant current source F. Connected to. Therefore, as shown in FIG. 5, the constant current source F flows into the output terminal with a limited current I2, and the transistor Tr flows out more outflow current I1 than the above-mentioned inflow current.
[0044]
On the other hand, in the output buffer circuit of FIG. 6, the transistor Tr is P-type, the collector is connected to the low-level power supply, the emitter is connected to the output terminal, and the transistor Tr is connected to the high level via the constant current source F. Connected to level power. Therefore, as shown in FIG. 6, the constant current source F flows out the limited current I2 to the output terminal, and the transistor Tr flows in more inflow current I1 than the outflow current.
[0045]
Here, as described above, it is assumed that C1 ≠ C2 and C1 前述 C2. For example, R = 10 kΩ, C1 = 10 pF, and C2 = 1000 pF. In this case, for the signal frequency f1 of the transimpedance amplifier 2, the time constants t1 and t2 at the respective output load capacitances C1 and C2 are represented by C1.R and C2.R, and C1.R: C2. R = 1: 100.
[0046]
If no oscillation occurs in the transimpedance amplifier 2, the output voltage when the first output load capacitor C1 is connected to the output terminal is Vo1, and the output voltage when the second output load capacitor C2 is connected is Vo2. Then, in the measuring device 13, as shown in FIG. 10, the output is performed within the reference value range of the appropriate output value, and the output difference ΔV = Vo2−Vo1 ≒ 0.
[0047]
On the other hand, when oscillation occurs, the first output load capacitance C1 has a small capacitance value, so that the output voltage Vo1 is sufficiently charged and discharged by the output buffer circuit in the first output load capacitance C1. Have the ability to
| I1 · t / C1 | = | I2 · t / C1 | (where I2≪I1)
It becomes. Accordingly, as shown in FIG. 9, the output oscillation waveform is not distorted, that is, follows the input waveform, and the smoothed output voltage Vave2 falls within the reference value range of the appropriate output value, and is determined to be a defective oscillation product. Not done.
[0048]
However, the second output load capacitance C2 has such a large capacitance value that the output oscillation waveform is distorted, that is, does not follow the input waveform and is flattened. Therefore, in the output buffer circuit of FIG. 5 in which the output load capacitance C2 is charged with the unrestricted current value I1 and discharged with the restricted current value I2, the output voltage Vo2 has a sufficient capacity for the output load capacitance C2. However, the speed at which the charge is stored in the output load capacitance C2 can follow the oscillation waveform because the ability to discharge is insufficient, but the outflow current I2 is limited, so that it cannot follow the oscillation waveform.
| I1 · t / C2 | ≫ | I2 · t / C2 | (where I2≪I1)
It becomes. Therefore, as shown in FIG. 2, the output oscillation waveform is distorted, and the output difference ΔV = Vave3−Vave2 between the smoothed output voltage Vave3 and the output voltage Vave2 falls outside the reference value range of the appropriate output value. Product.
[0049]
Conversely, in the output buffer circuit of FIG. 6 in which the output load capacitance C2 is discharged with the unrestricted current value I1 and charged with the restricted current value I2, the output voltage Vo2 is sufficiently discharged to the output load capacitance C2. Although it has the capability, the charging ability is insufficient, so that the speed at which the electric charge flows out of the output load capacitance C2 can follow the oscillation waveform, but the inflow current I2 is limited, so that it cannot follow the oscillation waveform. ,
| I1 · t / C2 | ≫ | I2 · t / C2 | (where I2≪I1)
It becomes. Therefore, as shown in FIG. 3, the output oscillation waveform is distorted, and the output difference ΔV = Vave4−Vave2 between the smoothed output voltage Vave4 and the output voltage Vave2 falls outside the reference range of the appropriate output value. Product.
[0050]
By comparing the output difference ΔVo = Vave3−Vave2 or ΔVo = Vave4−Vave2 between the output voltages Vo1 and Vo2 obtained by switching the output load capacitances C1 and C2, the oscillation of the optical disk pickup element 1 can be accurately detected. The presence or absence can be determined.
[0051]
Further, by switching between a small output load capacitance C1 in which the oscillation waveform is not distorted and an output load capacitance C2 sufficiently large so that the oscillation waveform is distorted, and judging the oscillation from the presence or absence of the output difference, the presence or absence of oscillation can be determined more accurately. Can be determined.
[0052]
Further, in order to further improve the determination accuracy, the output load capacitances C1 and C2 are switched a plurality of times, and an average value of the output voltages Vo1 and Vo2 at the respective output load capacitances C1 and C2 is obtained. The presence or absence of oscillation may be determined from the difference between the values.
[0053]
Further, in the inspection device 21 described above, the output load circuit 22 includes the first output load capacitance C1, the second output load capacitance C2, the resistor R, and the changeover switch SW. Switching between C1 and C2 can be realized with a simple configuration.
[0054]
Furthermore, in the inspection device 21 described above, the changeover switch SW selects the first output load capacitance C1 and the second output load capacitance C2 having different capacitance values from each other, thereby changing the output load capacitance. Although the switching is performed, even if the capacitors have the same capacitance value, the output load capacitance may be switched by switching the number of parallel connections or the number of series connections.
[0055]
Japanese Patent Application Laid-Open No. 64-61106 discloses an operational amplifier circuit device that switches a plurality of capacitive elements while detecting the presence or absence of oscillation to suppress oscillation. This shows an operational amplifier circuit device capable of adjusting the phase compensation capacitance to an optimum value that does not oscillate. The present invention in which the output load capacitances C1 and C2 are switched in an inspection device 21 for inspecting the presence or absence of oscillation is completely different from the present invention Are different.
[0056]
【The invention's effect】
As described above, the inspection method of a semiconductor device according to the present invention includes a pre-stage circuit having a gain, such as a transimpedance amplifier, and a constant-current output type output circuit that receives a current from the pre-stage circuit. For the semiconductor device to be connected, an output load defined by the specifications of the semiconductor device and set so as to be equivalent to a mounting substrate capacitance to which an output terminal is connected or an input resistance of a subsequent circuit is connected. In inspecting the semiconductor device, in particular, in determining the presence or absence of oscillation, a plurality of output load capacitors in the output load are provided and selectively connected, and the presence or absence of the oscillation is determined from each of the switched outputs. .
[0057]
Therefore, in the case of determining a defective oscillation product by determining that the amplitude of the output signal exceeds the range of the proper output value, with a single type of output load defined in the above specifications, the center value of the oscillation is equal to the proper output value. Only when the output value is greatly offset from the range, the output load capacity or the output smoothed by the inspection device is out of the range of the appropriate output value, and the defective oscillation product can be determined. If the output becomes within the range of the proper output value, the defective oscillation product cannot be determined.On the other hand, the output current of the constant current output type is changed by switching the output load capacitance. The possibility that the charge / discharge balance is lost and the smoothed output is out of the range of the appropriate output value is increased, and it can be determined that the product is an oscillation defective product. As a result, the accuracy of determining a defective oscillation product can be improved.
[0058]
Further, in the semiconductor device inspection method of the present invention, as described above, the presence or absence of oscillation is determined from the output difference due to the switching of the output load capacitance.
[0059]
Therefore, even if there is an offset between the semiconductor device and the measuring apparatus, the offset is removed by obtaining the output difference as a result of switching the output load capacitance, thereby further improving the accuracy of determining a defective oscillator. Can be.
[0060]
Still further, as described above, the semiconductor device inspection method of the present invention performs the switching of the output load capacitance a plurality of times, obtains an average value of the output at each output load capacitance, and calculates a difference between the average values. Determine the presence or absence of oscillation.
[0061]
Therefore, the determination accuracy can be further improved.
[0062]
Further, as described above, the semiconductor device inspection device of the present invention includes a pre-stage circuit having a gain, such as a transimpedance amplifier, and a constant current output type output circuit that receives a current from the pre-stage circuit as an input. Connected to an output load, which is specified in the specifications of the semiconductor device and is set to be equivalent to a mounting substrate capacity to which an output terminal is connected, an input resistance of a subsequent circuit, and the like. In testing the semiconductor device, in particular, in judging the presence or absence of oscillation, a plurality of output load capacitances in the output load are provided and selectively connected by the switching means. Means determines the presence or absence of the oscillation.
[0063]
Therefore, in the case of determining a defective oscillation product by determining that the amplitude of the output signal exceeds the range of the proper output value, with a single type of output load defined in the above specifications, the center value of the oscillation is equal to the proper output value. Only when the output value is greatly offset from the range, the output load capacity or the output smoothed by the inspection device is out of the range of the appropriate output value, and the defective oscillation product can be determined. If the output becomes within the range of the proper output value, the defective oscillation product cannot be determined.On the other hand, the output current of the constant current output type is changed by switching the output load capacitance. The possibility that the charge / discharge balance is lost and the smoothed output is out of the range of the appropriate output value is increased, and it can be determined that the product is an oscillation defective product. As a result, the accuracy of determining a defective oscillation product can be improved.
[0064]
Furthermore, in the semiconductor device inspection device of the present invention, as described above, the determination unit determines the presence or absence of oscillation from the output difference caused by switching the output load capacitance.
[0065]
Therefore, even if there is an offset between the semiconductor device and the measuring apparatus, the offset is removed by obtaining the output difference as a result of switching the output load capacitance, thereby further improving the accuracy of determining a defective oscillator. Can be.
[0066]
Further, as described above, the semiconductor device inspection device of the present invention uses the output load capacitance by selectively switching between the first output load capacitance and the second output load capacitance by the switching means.
[0067]
Therefore, the switching of the output load capacity can be realized with a simple configuration.
[0068]
Still further, as described above, the semiconductor device inspection device of the present invention can reduce the first output load capacitance so that the output oscillation waveform of the output circuit is not distorted with respect to the oscillation frequency of the semiconductor device. The second output load capacitance is set to a large capacitance value such that the output oscillation waveform of the output circuit is distorted.
[0069]
Therefore, the presence or absence of oscillation can be more accurately determined.
[0070]
Further, in the semiconductor device inspection device of the present invention, as described above, the output circuit is configured by the emitter follower type buffer including the transistor Tr and the constant current source F, and the second output load capacitance C2 is The capacitance value is set such that waveform distortion does not occur at the unlimited output current value I1 via the transistor Tr and waveform distortion occurs at the limited current value I2 via the constant current source F.
[0071]
Therefore, by comparing the difference between the output voltages Vo1 and Vo2 whose output load capacitances have been switched, the presence or absence of oscillation of the semiconductor device can be accurately determined.
[Brief description of the drawings]
FIG. 1 is a block diagram of an inspection apparatus according to an embodiment of the present invention.
FIG. 2 is an example of an output oscillation waveform according to the present invention when an optical pickup device for performing a characteristic test has an oscillation failure.
FIG. 3 is another example of an output oscillation waveform according to the present invention when an optical disc pickup element for performing a characteristic test has an oscillation failure.
FIG. 4 is a block diagram illustrating an electrical configuration of a pickup element for an optical disc, which is an example of a semiconductor device including a high-gain, wide-band transimpedance amplifier and a constant current output type output buffer circuit.
FIG. 5 is an electric circuit diagram showing a typical example of an output buffer circuit in the optical disk pickup device shown in FIG. 4;
FIG. 6 is an electric circuit diagram showing another typical example of the output buffer circuit in the optical disk pickup device shown in FIG. 4;
FIG. 7 is a block diagram of a typical prior art inspection device.
FIG. 8 is an example of an output oscillation waveform when an optical disc pickup element for performing a characteristic test has an oscillation failure.
FIG. 9 is another example of an output oscillation waveform when an optical disc pickup element for performing a characteristic test has an oscillation failure.
FIG. 10 is an example of an output oscillation waveform in a case where an optical disc pickup element for performing a characteristic test does not cause an oscillation failure.
[Explanation of symbols]
1 Optical disk pickup element (semiconductor device)
2 Transimpedance amplifier (pre-stage circuit)
3 Output buffer circuit (output circuit)
21 Inspection device
22 Output load circuit
23 Measuring device (judgment means)
C1, C2 output load capacity
F constant current source
PD photodiode
R resistance
Rf feedback resistor
SW changeover switch (changeover means)
Tr transistor

Claims (8)

In a test method for determining the presence or absence of oscillation of a semiconductor device including a pre-stage circuit having a gain and a constant-current output type output circuit that receives a current from the pre-stage circuit,
A method for testing a semiconductor device, comprising selectively connecting a plurality of output load capacitors to an output terminal. 2. The method according to claim 1, wherein the presence or absence of oscillation is determined from an output difference caused by switching the output load capacitance. 3. The semiconductor device according to claim 2, wherein the switching of the output load capacitance is performed a plurality of times, an average value of the output at each output load capacitance is obtained, and the presence or absence of oscillation is determined from a difference between the average values. Inspection method. In a test device for determining the presence or absence of oscillation of a semiconductor device including a pre-stage circuit having a gain and a constant current output type output circuit that receives a current from the pre-stage circuit,
Multiple output load capacities,
Switching means for selectively connecting the output load capacity to an output terminal of the semiconductor device; and determining means for determining the presence or absence of the oscillation from an output by the output load capacity switched by the switching means. Inspection equipment for semiconductor devices. 5. The semiconductor device inspection apparatus according to claim 4, wherein said determination means determines the presence or absence of oscillation based on an output difference caused by switching of said output load capacitance. The output load includes a parallel circuit of an output load capacitance and a resistor connected between an output terminal of the semiconductor device and a fixed potential, and includes a first output load capacitance and a second output load capacitance as the output load capacitance. 6. A semiconductor according to claim 5, wherein a switch constituting said switching means connects the first output load capacity and the second output load capacity to the output terminal alternatively. Equipment inspection equipment. The first output load capacitance is set to a small capacitance value such that the output oscillation waveform of the output circuit is not distorted with respect to the oscillation frequency of the semiconductor device, and the second output load capacitance is set to the output circuit 7. The semiconductor device inspection apparatus according to claim 6, wherein a large capacitance value is set such that the output oscillation waveform is distorted. The output circuit is configured such that a series circuit of a transistor Tr and a constant current source F is connected between power supply lines, and an emitter configured so that a connection point between the emitter of the transistor Tr and the constant current source F becomes the output terminal. Follower type buffer,
The second output load capacitance C2 has such a capacitance value that does not cause waveform distortion at the unlimited output current value I1 via the transistor Tr and causes waveform distortion at the limited current value I2 via the constant current source F. The inspection apparatus for a semiconductor device according to claim 7, wherein the inspection apparatus is set to:

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