CA1307939C - Method of adjusting bridge circuit of semiconductor - Google Patents
Method of adjusting bridge circuit of semiconductorInfo
- Publication number
- CA1307939C CA1307939C CA000551253A CA551253A CA1307939C CA 1307939 C CA1307939 C CA 1307939C CA 000551253 A CA000551253 A CA 000551253A CA 551253 A CA551253 A CA 551253A CA 1307939 C CA1307939 C CA 1307939C
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- adjusting
- bridge circuit
- pressure sensor
- semiconductor pressure
- resistance value
- Prior art date
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Abstract
ABSTRACT OF THE DISCLOSURE
A method of adjusting a bridge circuit of a semiconductor pressure sensor comprises the steps of providing conductive lines connected to at least one of diffused resistors at predetermined intervals during the wiring process, said diffused resistors being provided to connect strain gauge resistors constituting said bridge circuit; providing means for adjusting the resistance value of at least said one of said diffused resistors;
making vacuum suction to the back surface of a diaphragm of said semiconductor pressure sensor in the testing process to make a state wherein pressure is virtually applied to said diaphragm from the surface side thereof;
measuring the pressure sensitivity of said semiconductor pressure sensor from the surface side of the diaphragm by making use of said bridge circuit; and adjusting the resistance value of at least said one of said diffused resistors by said adjusting means based on the pressure sensitivity thus measured to adjust the balance of said bridge circuit.
A method of adjusting a bridge circuit of a semiconductor pressure sensor comprises the steps of providing conductive lines connected to at least one of diffused resistors at predetermined intervals during the wiring process, said diffused resistors being provided to connect strain gauge resistors constituting said bridge circuit; providing means for adjusting the resistance value of at least said one of said diffused resistors;
making vacuum suction to the back surface of a diaphragm of said semiconductor pressure sensor in the testing process to make a state wherein pressure is virtually applied to said diaphragm from the surface side thereof;
measuring the pressure sensitivity of said semiconductor pressure sensor from the surface side of the diaphragm by making use of said bridge circuit; and adjusting the resistance value of at least said one of said diffused resistors by said adjusting means based on the pressure sensitivity thus measured to adjust the balance of said bridge circuit.
Description
:~L3~7939 METHOD OF ADJUSTING BRIDGE CIRCUIT ~F SEMIC()NDUCTOR
PP~ESSURE SENSOR
BACKGROUND OF THE INVENTION
This invention relates to a method of adjusting a bridge circuit of a aemiconductor pressure sensar under the wafer process and more specifically to a method of adjusting a bridge circuit of ~I semiconductor pressure sensor typical of a semiconduc1:or pressure sensor fitted to the tip of a catheter for medical use.
When a mechanical stress is applied to a semiconductor crystal of silicon or the l.ike, its resistance.changes greatly because of the piezoelectric resistance effect t and the perception of this :Eact has led to the development of a semiconductor pressure sensor. The process of makiny such a semiconductor pressure sensor comprises the steps ~ of formung a st~n gauge resis~r by diffusion of impurity ions on the ~ace layer of a silicon single crystal, as.sembling~four .' of the strain gauge resistor.s into a Wheatstone bridge, : forming a recess in the back surface of the silicon : monocrystal by etching, and disposing electrodes in suitable places on the surface thereof with the thin portion as a disphragm. When pressure is applied to the semiconductor pressur~ sensor, the diaphragm is deformed and the resistance value of the strain gauge resistor changes to a greater extent because of the piezoelectric ~k . ~ .
:
~ ,.
1 resistance effect, so that a bridge output proportional to the pressure is obtainable.
The aforesaid semiconductor pressure sensor is extremely small in size and, particularly in the case of a semiconductor pressltre sensor for medical use, a plurality of semiconductor pressure sensors are fitted to the tip of a catheter and inserted into a body.
Accordingly, even in a semiconductor pressure sensor incorpora~ing peripheral circuits such as a temperature compensating circuit, a pressure sensitivity compensatillg circuit and the like, a side of a chip should be about 1 mm or smaller in length.
Variations in resistance value of each of the strain gauge resistors and diffused resistors at their formation and uninformity in the thickness of the diaphragm produced by the etching process resu].t in variations in the characteristics of the semiconductor pressure sensorO
However, the semiconductor pressure sensor i5 e~tremely small in size and it is very difficult to measure the electrical characteristics while pressure is being appl1ed actually and adjust the resistance balance of the bridge circuit. Actually, the measurement of such electrical characteristics while the pressure i5 being applied is omitted, whereas only the electrical characteristics of the bridge circuit are measured to ., .
.
~ "
~3~7~39 1 find and discard what exceed a predetermined tolerance as inferior goods.
Accordingly, yields of the semiconductor pressure sensor are poor and, in addition to this problem, the measurement of electrical characteristics has posed lack ; of reliability because the degree of deformation of the diaphragm resulting from the pressure actually applied thereto is not measured.
SUM~ARY OF THE INVENTIO~
In view of the aforesaid problems, an object of the ; pr~sent invention is to provide a method of adjusting a bridge circuit of a semiconcluctor pressure sensor to improve yields by adjusting the output balance of the bridge circuit based on the output of the semiconductor pressure sensor in a state c:losely approximated to that wherein the semiconductor pressure sensor i5 actually in use.
In order to accomplish the aforesaid object, the method of adjusting the bridge circuit of a semiconductor pressure sensor comprises the steps of forming the principal part of the bridge circuit consisting of strain gauge resistors and diffused resistors connecting the strain gauge resistors during the diffusion process of a diaphragm type semiconductor pressure sensor, providing conductive 11nP~ connected to at least one of ~L3~7~33g 1 the diffused resistors at predetermined intervals during the wiring process, providing an Al pad common to the ends of the conductive lLnes, mRking vacuum suction to the back surface of the diaphragm in the testing process to create a state wherein press~lre is virtually applied to the diaphragm from the surface side thereof, measuring the pressure sensitivity of the semiconductor pressure sensor from the surface side of the diaphragm by making use of the bridge circuitl and selectively cutting the conductive lines based on the pressure sensitivity thus measured to adjust the output balance of he bridge circuit by adjusting the resistance value of the diffused resistor~
On the other hand, during the wiring process, pads may be installed at the erLds of respective conductive 7;nes and one of the pads may be selected and bonded based o~ the pressure sensitivity : of the semiconductor pressure sensor to adjust the output balance of the bri~ge circuit~
In the method of adjusting the bridge circuit of a semiconductor pressure sensor, the diaphragm issubJected to vacuum suction from its back surface side to subject the diaphragm to negative pressure during the testing process and the resistance value of the strain gauge resistor forming the principal part of the bridge circuit fo~med on the .
:.
,. ' ~ ` ' :
., .
~3~g39 1 diaphragm is caused to change through the deformation of the diaphragm and the piezoelectric resistance effect.
The changes in the output of the bridge circuit can be measured by making use of the electrodes formed on the surface of the semiconductor prlessure sensor.
The resistance value can be set stepwise by providlng the - lines connected tothe dif~used resistor at the predetermined intervals and the diffused resistor is distributed by selectively cutting the lines or bonding one pad whereby the resistance value can simply be ad]usted.
Accordingly, before the wafer is diced, ii is possible to adjust the brid~e circuit of the semiconductor pressure sensor readily by adjusting the resistance balance of the bridge circuit while pressure is being applied thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic top view showing a method of adjusting a bridge circuit of a semiconductor pressure sensor according to a first embodiment of the present invention.
Fig. 2 is a cross sectional view of the semicondu~tor pressure sensor of Fig. 1.
Fi~o 3 is a schematic sectional view showing an embodiment for measuring the pressure sensitivity of the semiconductor pressure sensor.
, ~3~793g l Fig. ~ is a diagram showing a state wherein pressure is applied to the semiconductor pressure sensor.
FigO 5 is an electric circuit diagram showing an electrical arrangement of the semiconductor pressure sensor of Fig. lo ~; Fig. 6 is a schematic top view showing a method of adjusting a bridge circuit of a semiconductor pressure sensor according to a seccnd emxX~nent of the present invention.
Fig. 7 is a cross sectional view of the semiconductor pressuxe sensor of FigO 6.
Fig. 8 is an electric circuit diagxam showing an electrical arrangement of the semiconductor pressure sensor of Fig. 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the accompanying drawings, embodiments of the present invention will be described in detail.
Fig. 1 is a schematic ~op view showing a method of adjus~ing a bridge circuit of a semiconductor pressure sensor according to a first embodiment of the present invention~ Fig. 2 is a schematic cross sectional view of the semiconductor pressure sensor. In Figs. 1 and 2, a semiconductor pressure sensor 1 is extremely~small with a thickness of about 400 um and p~ type strain gauge resistors 3a, 3b, 3c, 3d of several kQ are formed on the surface of a substrate 2 composed of an n~ type ~3~7~3~ ~
1 silicon single srys~. Four of the strain gauge resistors are wired in sexies using p~ diffused resistors 4 which are - extended around the surface of the substrate 2 and AQ pads 5a, 5b, 5c, 5d, 5e are formed on the diffused resistors 4 thus extended. Moreover, a recess 6 is formed in the back surface of the silicon single crystal 2 with a thin portion ~with a thickness of less than 30um) used as a diaphragm 7.
In addition to the construction of the aforesaid known semiconductor pressure sensor 1, an AQ pad 8 is installed and lines 9 of an electric conductor ~for example, aluminum,gold, silver, copper, etc.~ are provided to be ! connected to the diffused resistor 4 wired between the AQ
pad 5e and the strain gauge resistor 3d at predetermined intervals. The ends of the all lines 9 are connected to the AQ pad 8.
The AQ pads 8 and 5e are connected and further the AQ pads 5e and 5a are connected. Voltage is applied across the AQ pads 8 ~5e) and AQ pad 5c to obtain an output between the AQ pads 5b and 5d. That is, a bridge circuit is arranged (see Fig. 5). In Fig. 5, r1 ~ r8 represent the resistance values of the diffused resistors 4. The adjustment of the output balance of the bridge circuit is made by selectively cutting the lines 9 by a laser beam and adjusting the resistance value ~r~l ~3~793~
1 between the AQ pad 5e and the resistor 3d.
The intervals at which the lines 9 are connected to the diffused resistor 4 are set according to the resistance characteristic (Q - m) of the resistor and, provided the resistance characteristic is linear, an equal interval is preferred~
The present invention is not limited to the afoxesaid embodiments. The AQ pads 5a ancl 5e are connected, for instance, and voltage is ap~lied across the AQ pads 8 and 5d, whereas the resistance value of not only the diffused resistor 4 between the AQ pad 5e and the straih ; gauge resistor 3d but also those of other diffused resistors may be made adjust:able, provided the combination and arrangement of parts are modified without departing from the ~prit and the scope of the invention as hereinafter claimed.
FigO ~ is a schematic t;op view showing a method of adjusting a bridge circuit of a semiconductor pressure sensor according to a second embodiment of the present invention. Fig~ 7 is a schematic cross sectional view of the semiconductor pressure sensor of Fig. 6. This embodiment is substantially the same as what is shown in FigO 1 except that AQ pads 8' are connected to the res~ective conductive lines 9.
In this embodiment, the AQ pads 5a and Se are ,`'; :' . ~
~3~7939 1 connected and voltage is applied across the A~ pads 5a, 5e and the A~ pad 8', whereas an output is taken out from between the AQ pads 5b and 5d. That is, a bridge circuit is thus arranged and any one of the AQ pads 8' is properly selected ?.nd bonded for the purpose of adjusting the resistance value r4 (r5) of the di~fused resistor 4 formed between the strain gauge resistors 3c and 3b as the wiring (see Fig. 8)o In Fig. 8, r r8 represent the resistance values of the diffused resistors 4.
A resistance adjusting circuit 110 in this embodiment may be arranged between not only the strain gauge resistors 3b and 3c but also other strain gauge resistors to effect the adjustment of the diffused resistors 4. Moreover, the intervals at which the :lines 9 are connected to the diffused resistor 4 are set according to the resistance characteristic (Q - m) of the resistor and, provided the resistance characteristic is linear, an equal interval is preferred.
Fig. 3 is a sch matic sectional view showing an example for measuring the pressure sensitivity of the semiconductor pressure sensor, wherein a wafer stage 10 has a vacuum leakage ~reventing seal material 12 of soft synthetic resin ~for example, styrene, butadiene or silicone ruhber) with a thickness in the order of _ g _ ,,, ~ . .. ~., ' ~ . ....
.~
~` ~3~793~
1 10 um, which is formed on a plate material 11 of stainless or synthetic resin. Further, at least one through-hole 13 is bored in a suftable place of the wafer stage 10 to make vacuu~-suction to a recess 6 of the semiconductor pressure sensor 1. The recess 6 of the semiconductor pressure sensor 1 is located above the through-hole 13. In the first embodiment shown in Fig. 1, the measuring probes 14 are caused to contact across the AQ pads 5a, 5e and th~
AQ pad Sc (between the input terminals of the bridge) ancl across the AQ pads 5b and 5d (between the output tel~inals thereof) provided on the surface of the semiconductor pressure sensor 1. In the second en~odiment shown in Fig. 6, the measuring probes 14 are caused to contact across the AQ pads 5a, 5e and the AQ
pad 8' (between the input terminals of the bridge) and across the ~Q pads 5b and Sd (between the output terminals thereof)~
In order to locate the recess 6 of the semiconductor pressure sensor 1 above the through-hole 13 of the wafer stage 10, the wafer 15 should be moved while the wafer stage 10 and the measuring probes 14 are set still or the wafer stage 10 and the measuring probes 14~should be shifted while the wafer lS is set still.
As set forth above, the wafer 15 is mounted on the wafer stage 10 and is subjected to vacuum suction using the through-. .... ~.
,~
' ~ ' , ~3~ 3~ ~
l hole 13 and the seal material on the wafer stage 10 prevents vacuum leakage through the connection between the silicon crystal 2 and the wafer stage 10. Moreover, the negative pressure corresponding ~o the pressure applied from the surface of the semiconductor pressure sensor 1 is generated at the recess 6 and the diaphrasm 7 is deformed as in the case where the pressure is applied thereto trom the surface.
Fig. 4 is a schematic view showing the diaphragm 7 thus deformed. ~he strain gauge resistors 3a and 3c formed by diffusion in the center of the diaphragm 7 out of the four strain gauge resistors 3a, 3b, 3c and 3d ! constituting the bridge ~ircuit as shown in FigO 5 or 8, are compressed, whereas the strain gause resistors 3b ; 15 and 3d diffused on the periphery of the diaphragm 7 are extended as the diaphragm 7 is deformed.
With respect to the strain gauge resistors, use is made of those whose resistance value increases propor~
tionally to the stressO Given the resistanoe values of the strain gauge resistors 3a, 3b, 3c and 3d respectively at Rl, R2, R3 and R4, R2 and R4 increases whereas Rl and R3 decreases as the diaphragm 7 deforms.
In other words, the potential Vl acrojs the terminals of the resistor 3b increases, whereasthe potential V2 across the terminals of the resistor 3c decreases.
13~7~3~
1 Accordingly, the bridge output, i.e., V1 - V2 increases in proportion to the deformation of the diaphragm 7.
The pressure sensitivity of the semiconductor pressure sensor l can be measured, before the wafer 15 is diced, by measuring the bridge output with the measuring probe 14 using the AQ pads of the semiconductor pressure sensor 1.
The output of the semiconductor pressure sensor is measured while the pressure is being applied thereto.
With respect to the semiconductor pressure sensor whose me.~sured value shows a slight error, the lines connected to the diffused resistor 4 are appropriately cut out by a la3er beam (first embodiment), or otherwise one of the AQ pads 8~ provided at respective lines 9 connected - to the diffused resistor 4 at the predetermined intervals is selected (second embodiment), whereby the resistance vaLue of the diffused resistor can ~e easily adjusted.
Therefore, the output balance of the bridge circuit of the semiconductor pressure sensor can be adjusted before the semiconductor pressure sensor is diced~
In a brief summary, the electrical measurçment is made from the surface side of the semiconductor pressure sensor 1 and the pressure is applied from the back surface side thereof, whereby the pressure se~sitivity .
. .
~3(:?7939 1 of the sem.iconductor pressure sensor 1 is measured under the testing process. With respect to the semiconductor pressure sensor showing error in the measurement, the output balance of its bridge circuit can be adjusted by adjusting the resistance value of the difused resistor 4.
As set forth above, in the method of adjusting the bridge circuit of the semiconductor pressure sensor according to the present invention, there is created a state in which pressure is virtually applied to the diaphragm from the back surface side of the semiconductor pressure sensor and the electrical output is measured in that state similar to that of actual use. Then the lines connected tothe diffused resistor at the predetermined intervals are suitably cut out or otherwise one of the Al pads provided at the respective lines connected to the diffused resistor at the predetermined intervals is properly selected and bonded so that the balance adjustment of the bridge circuit of the semiconductor pressure sensor can be made by adjusting the resistance value of the diffused resistor.
Accordingly, yields of the semiconductor pressùre sensor are improved.
~3~7939 1 ~lthough, in the above described embodiments, recesses 6 provided in the wafer 15 are subjected to vacuum suction one ~y one, all recesses may be subjected to vacuum suction simultaneously by providing a porous member, through which a gas can pass, between the wafer 15 and the wafer stage 10 provided the through-hole 13.
Also, in the above described embodiments, although one resistance value of a diffused resistor is adjusted, . any resistance values of any diffused resistors may be adjusted.
PP~ESSURE SENSOR
BACKGROUND OF THE INVENTION
This invention relates to a method of adjusting a bridge circuit of a aemiconductor pressure sensar under the wafer process and more specifically to a method of adjusting a bridge circuit of ~I semiconductor pressure sensor typical of a semiconduc1:or pressure sensor fitted to the tip of a catheter for medical use.
When a mechanical stress is applied to a semiconductor crystal of silicon or the l.ike, its resistance.changes greatly because of the piezoelectric resistance effect t and the perception of this :Eact has led to the development of a semiconductor pressure sensor. The process of makiny such a semiconductor pressure sensor comprises the steps ~ of formung a st~n gauge resis~r by diffusion of impurity ions on the ~ace layer of a silicon single crystal, as.sembling~four .' of the strain gauge resistor.s into a Wheatstone bridge, : forming a recess in the back surface of the silicon : monocrystal by etching, and disposing electrodes in suitable places on the surface thereof with the thin portion as a disphragm. When pressure is applied to the semiconductor pressur~ sensor, the diaphragm is deformed and the resistance value of the strain gauge resistor changes to a greater extent because of the piezoelectric ~k . ~ .
:
~ ,.
1 resistance effect, so that a bridge output proportional to the pressure is obtainable.
The aforesaid semiconductor pressure sensor is extremely small in size and, particularly in the case of a semiconductor pressltre sensor for medical use, a plurality of semiconductor pressure sensors are fitted to the tip of a catheter and inserted into a body.
Accordingly, even in a semiconductor pressure sensor incorpora~ing peripheral circuits such as a temperature compensating circuit, a pressure sensitivity compensatillg circuit and the like, a side of a chip should be about 1 mm or smaller in length.
Variations in resistance value of each of the strain gauge resistors and diffused resistors at their formation and uninformity in the thickness of the diaphragm produced by the etching process resu].t in variations in the characteristics of the semiconductor pressure sensorO
However, the semiconductor pressure sensor i5 e~tremely small in size and it is very difficult to measure the electrical characteristics while pressure is being appl1ed actually and adjust the resistance balance of the bridge circuit. Actually, the measurement of such electrical characteristics while the pressure i5 being applied is omitted, whereas only the electrical characteristics of the bridge circuit are measured to ., .
.
~ "
~3~7~39 1 find and discard what exceed a predetermined tolerance as inferior goods.
Accordingly, yields of the semiconductor pressure sensor are poor and, in addition to this problem, the measurement of electrical characteristics has posed lack ; of reliability because the degree of deformation of the diaphragm resulting from the pressure actually applied thereto is not measured.
SUM~ARY OF THE INVENTIO~
In view of the aforesaid problems, an object of the ; pr~sent invention is to provide a method of adjusting a bridge circuit of a semiconcluctor pressure sensor to improve yields by adjusting the output balance of the bridge circuit based on the output of the semiconductor pressure sensor in a state c:losely approximated to that wherein the semiconductor pressure sensor i5 actually in use.
In order to accomplish the aforesaid object, the method of adjusting the bridge circuit of a semiconductor pressure sensor comprises the steps of forming the principal part of the bridge circuit consisting of strain gauge resistors and diffused resistors connecting the strain gauge resistors during the diffusion process of a diaphragm type semiconductor pressure sensor, providing conductive 11nP~ connected to at least one of ~L3~7~33g 1 the diffused resistors at predetermined intervals during the wiring process, providing an Al pad common to the ends of the conductive lLnes, mRking vacuum suction to the back surface of the diaphragm in the testing process to create a state wherein press~lre is virtually applied to the diaphragm from the surface side thereof, measuring the pressure sensitivity of the semiconductor pressure sensor from the surface side of the diaphragm by making use of the bridge circuitl and selectively cutting the conductive lines based on the pressure sensitivity thus measured to adjust the output balance of he bridge circuit by adjusting the resistance value of the diffused resistor~
On the other hand, during the wiring process, pads may be installed at the erLds of respective conductive 7;nes and one of the pads may be selected and bonded based o~ the pressure sensitivity : of the semiconductor pressure sensor to adjust the output balance of the bri~ge circuit~
In the method of adjusting the bridge circuit of a semiconductor pressure sensor, the diaphragm issubJected to vacuum suction from its back surface side to subject the diaphragm to negative pressure during the testing process and the resistance value of the strain gauge resistor forming the principal part of the bridge circuit fo~med on the .
:.
,. ' ~ ` ' :
., .
~3~g39 1 diaphragm is caused to change through the deformation of the diaphragm and the piezoelectric resistance effect.
The changes in the output of the bridge circuit can be measured by making use of the electrodes formed on the surface of the semiconductor prlessure sensor.
The resistance value can be set stepwise by providlng the - lines connected tothe dif~used resistor at the predetermined intervals and the diffused resistor is distributed by selectively cutting the lines or bonding one pad whereby the resistance value can simply be ad]usted.
Accordingly, before the wafer is diced, ii is possible to adjust the brid~e circuit of the semiconductor pressure sensor readily by adjusting the resistance balance of the bridge circuit while pressure is being applied thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic top view showing a method of adjusting a bridge circuit of a semiconductor pressure sensor according to a first embodiment of the present invention.
Fig. 2 is a cross sectional view of the semicondu~tor pressure sensor of Fig. 1.
Fi~o 3 is a schematic sectional view showing an embodiment for measuring the pressure sensitivity of the semiconductor pressure sensor.
, ~3~793g l Fig. ~ is a diagram showing a state wherein pressure is applied to the semiconductor pressure sensor.
FigO 5 is an electric circuit diagram showing an electrical arrangement of the semiconductor pressure sensor of Fig. lo ~; Fig. 6 is a schematic top view showing a method of adjusting a bridge circuit of a semiconductor pressure sensor according to a seccnd emxX~nent of the present invention.
Fig. 7 is a cross sectional view of the semiconductor pressuxe sensor of FigO 6.
Fig. 8 is an electric circuit diagxam showing an electrical arrangement of the semiconductor pressure sensor of Fig. 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the accompanying drawings, embodiments of the present invention will be described in detail.
Fig. 1 is a schematic ~op view showing a method of adjus~ing a bridge circuit of a semiconductor pressure sensor according to a first embodiment of the present invention~ Fig. 2 is a schematic cross sectional view of the semiconductor pressure sensor. In Figs. 1 and 2, a semiconductor pressure sensor 1 is extremely~small with a thickness of about 400 um and p~ type strain gauge resistors 3a, 3b, 3c, 3d of several kQ are formed on the surface of a substrate 2 composed of an n~ type ~3~7~3~ ~
1 silicon single srys~. Four of the strain gauge resistors are wired in sexies using p~ diffused resistors 4 which are - extended around the surface of the substrate 2 and AQ pads 5a, 5b, 5c, 5d, 5e are formed on the diffused resistors 4 thus extended. Moreover, a recess 6 is formed in the back surface of the silicon single crystal 2 with a thin portion ~with a thickness of less than 30um) used as a diaphragm 7.
In addition to the construction of the aforesaid known semiconductor pressure sensor 1, an AQ pad 8 is installed and lines 9 of an electric conductor ~for example, aluminum,gold, silver, copper, etc.~ are provided to be ! connected to the diffused resistor 4 wired between the AQ
pad 5e and the strain gauge resistor 3d at predetermined intervals. The ends of the all lines 9 are connected to the AQ pad 8.
The AQ pads 8 and 5e are connected and further the AQ pads 5e and 5a are connected. Voltage is applied across the AQ pads 8 ~5e) and AQ pad 5c to obtain an output between the AQ pads 5b and 5d. That is, a bridge circuit is arranged (see Fig. 5). In Fig. 5, r1 ~ r8 represent the resistance values of the diffused resistors 4. The adjustment of the output balance of the bridge circuit is made by selectively cutting the lines 9 by a laser beam and adjusting the resistance value ~r~l ~3~793~
1 between the AQ pad 5e and the resistor 3d.
The intervals at which the lines 9 are connected to the diffused resistor 4 are set according to the resistance characteristic (Q - m) of the resistor and, provided the resistance characteristic is linear, an equal interval is preferred~
The present invention is not limited to the afoxesaid embodiments. The AQ pads 5a ancl 5e are connected, for instance, and voltage is ap~lied across the AQ pads 8 and 5d, whereas the resistance value of not only the diffused resistor 4 between the AQ pad 5e and the straih ; gauge resistor 3d but also those of other diffused resistors may be made adjust:able, provided the combination and arrangement of parts are modified without departing from the ~prit and the scope of the invention as hereinafter claimed.
FigO ~ is a schematic t;op view showing a method of adjusting a bridge circuit of a semiconductor pressure sensor according to a second embodiment of the present invention. Fig~ 7 is a schematic cross sectional view of the semiconductor pressure sensor of Fig. 6. This embodiment is substantially the same as what is shown in FigO 1 except that AQ pads 8' are connected to the res~ective conductive lines 9.
In this embodiment, the AQ pads 5a and Se are ,`'; :' . ~
~3~7939 1 connected and voltage is applied across the A~ pads 5a, 5e and the A~ pad 8', whereas an output is taken out from between the AQ pads 5b and 5d. That is, a bridge circuit is thus arranged and any one of the AQ pads 8' is properly selected ?.nd bonded for the purpose of adjusting the resistance value r4 (r5) of the di~fused resistor 4 formed between the strain gauge resistors 3c and 3b as the wiring (see Fig. 8)o In Fig. 8, r r8 represent the resistance values of the diffused resistors 4.
A resistance adjusting circuit 110 in this embodiment may be arranged between not only the strain gauge resistors 3b and 3c but also other strain gauge resistors to effect the adjustment of the diffused resistors 4. Moreover, the intervals at which the :lines 9 are connected to the diffused resistor 4 are set according to the resistance characteristic (Q - m) of the resistor and, provided the resistance characteristic is linear, an equal interval is preferred.
Fig. 3 is a sch matic sectional view showing an example for measuring the pressure sensitivity of the semiconductor pressure sensor, wherein a wafer stage 10 has a vacuum leakage ~reventing seal material 12 of soft synthetic resin ~for example, styrene, butadiene or silicone ruhber) with a thickness in the order of _ g _ ,,, ~ . .. ~., ' ~ . ....
.~
~` ~3~793~
1 10 um, which is formed on a plate material 11 of stainless or synthetic resin. Further, at least one through-hole 13 is bored in a suftable place of the wafer stage 10 to make vacuu~-suction to a recess 6 of the semiconductor pressure sensor 1. The recess 6 of the semiconductor pressure sensor 1 is located above the through-hole 13. In the first embodiment shown in Fig. 1, the measuring probes 14 are caused to contact across the AQ pads 5a, 5e and th~
AQ pad Sc (between the input terminals of the bridge) ancl across the AQ pads 5b and 5d (between the output tel~inals thereof) provided on the surface of the semiconductor pressure sensor 1. In the second en~odiment shown in Fig. 6, the measuring probes 14 are caused to contact across the AQ pads 5a, 5e and the AQ
pad 8' (between the input terminals of the bridge) and across the ~Q pads 5b and Sd (between the output terminals thereof)~
In order to locate the recess 6 of the semiconductor pressure sensor 1 above the through-hole 13 of the wafer stage 10, the wafer 15 should be moved while the wafer stage 10 and the measuring probes 14 are set still or the wafer stage 10 and the measuring probes 14~should be shifted while the wafer lS is set still.
As set forth above, the wafer 15 is mounted on the wafer stage 10 and is subjected to vacuum suction using the through-. .... ~.
,~
' ~ ' , ~3~ 3~ ~
l hole 13 and the seal material on the wafer stage 10 prevents vacuum leakage through the connection between the silicon crystal 2 and the wafer stage 10. Moreover, the negative pressure corresponding ~o the pressure applied from the surface of the semiconductor pressure sensor 1 is generated at the recess 6 and the diaphrasm 7 is deformed as in the case where the pressure is applied thereto trom the surface.
Fig. 4 is a schematic view showing the diaphragm 7 thus deformed. ~he strain gauge resistors 3a and 3c formed by diffusion in the center of the diaphragm 7 out of the four strain gauge resistors 3a, 3b, 3c and 3d ! constituting the bridge ~ircuit as shown in FigO 5 or 8, are compressed, whereas the strain gause resistors 3b ; 15 and 3d diffused on the periphery of the diaphragm 7 are extended as the diaphragm 7 is deformed.
With respect to the strain gauge resistors, use is made of those whose resistance value increases propor~
tionally to the stressO Given the resistanoe values of the strain gauge resistors 3a, 3b, 3c and 3d respectively at Rl, R2, R3 and R4, R2 and R4 increases whereas Rl and R3 decreases as the diaphragm 7 deforms.
In other words, the potential Vl acrojs the terminals of the resistor 3b increases, whereasthe potential V2 across the terminals of the resistor 3c decreases.
13~7~3~
1 Accordingly, the bridge output, i.e., V1 - V2 increases in proportion to the deformation of the diaphragm 7.
The pressure sensitivity of the semiconductor pressure sensor l can be measured, before the wafer 15 is diced, by measuring the bridge output with the measuring probe 14 using the AQ pads of the semiconductor pressure sensor 1.
The output of the semiconductor pressure sensor is measured while the pressure is being applied thereto.
With respect to the semiconductor pressure sensor whose me.~sured value shows a slight error, the lines connected to the diffused resistor 4 are appropriately cut out by a la3er beam (first embodiment), or otherwise one of the AQ pads 8~ provided at respective lines 9 connected - to the diffused resistor 4 at the predetermined intervals is selected (second embodiment), whereby the resistance vaLue of the diffused resistor can ~e easily adjusted.
Therefore, the output balance of the bridge circuit of the semiconductor pressure sensor can be adjusted before the semiconductor pressure sensor is diced~
In a brief summary, the electrical measurçment is made from the surface side of the semiconductor pressure sensor 1 and the pressure is applied from the back surface side thereof, whereby the pressure se~sitivity .
. .
~3(:?7939 1 of the sem.iconductor pressure sensor 1 is measured under the testing process. With respect to the semiconductor pressure sensor showing error in the measurement, the output balance of its bridge circuit can be adjusted by adjusting the resistance value of the difused resistor 4.
As set forth above, in the method of adjusting the bridge circuit of the semiconductor pressure sensor according to the present invention, there is created a state in which pressure is virtually applied to the diaphragm from the back surface side of the semiconductor pressure sensor and the electrical output is measured in that state similar to that of actual use. Then the lines connected tothe diffused resistor at the predetermined intervals are suitably cut out or otherwise one of the Al pads provided at the respective lines connected to the diffused resistor at the predetermined intervals is properly selected and bonded so that the balance adjustment of the bridge circuit of the semiconductor pressure sensor can be made by adjusting the resistance value of the diffused resistor.
Accordingly, yields of the semiconductor pressùre sensor are improved.
~3~7939 1 ~lthough, in the above described embodiments, recesses 6 provided in the wafer 15 are subjected to vacuum suction one ~y one, all recesses may be subjected to vacuum suction simultaneously by providing a porous member, through which a gas can pass, between the wafer 15 and the wafer stage 10 provided the through-hole 13.
Also, in the above described embodiments, although one resistance value of a diffused resistor is adjusted, . any resistance values of any diffused resistors may be adjusted.
Claims (3)
1. A method of adjusting a bridge circuit of a semiconductor pressure sensor, comprising the steps of:
providing conductive lines connected to at least one of diffused resistors at predetermined intervals during the wiring process, said diffused resistors being provided to connect strain gauge resistors constituting said bridge circuit;
providing means for adjusting the resistance value of at least said one of said diffused resistors:
making vacuum suction to the back surface of a diaphragm of said semiconductor pressure sensor in the testing process to make a state wherein pressure is virtually applied to said diaphragm from the surface side thereof;
measuring the pressure sensitivity of said semiconductor pressure sensor from the surface side of the diaphragm by making use of said bridge circuit: and adjusting the resistance value of at least said one of said diffused resistors by said adjusting means based on the pressure sensitivity thus measured to adjust the balance of said bridge circuit.
providing conductive lines connected to at least one of diffused resistors at predetermined intervals during the wiring process, said diffused resistors being provided to connect strain gauge resistors constituting said bridge circuit;
providing means for adjusting the resistance value of at least said one of said diffused resistors:
making vacuum suction to the back surface of a diaphragm of said semiconductor pressure sensor in the testing process to make a state wherein pressure is virtually applied to said diaphragm from the surface side thereof;
measuring the pressure sensitivity of said semiconductor pressure sensor from the surface side of the diaphragm by making use of said bridge circuit: and adjusting the resistance value of at least said one of said diffused resistors by said adjusting means based on the pressure sensitivity thus measured to adjust the balance of said bridge circuit.
2. A method of adjusting a bridge circuit of a semiconductor pressure sensor as claimed in claim 1, wherein said means for adjusting the resistance value . -15-consists of said lines and a conductive pad commonly connected to the ends of respective lines and wherein the resistance value of said diffused resistor is adjusted by selectively cutting out said lines based on said pressure sensitivity.
3. A method of adjusting a bridge circuit of a semiconductor pressure sensor as claimed in claim 1, wherein said means for adjusting the resistance value consists of said lines and conductive pads connected to respective ends of said lines and wherein the resistance value of said diffused resistor is adjusted by selecting and bonding one of said pads based on said pressure sensitivity.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP264747/86 | 1986-11-06 | ||
| JP61264747A JPS63118628A (en) | 1986-11-06 | 1986-11-06 | Adjusting method for bridge circuit of semiconductor pressure sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1307939C true CA1307939C (en) | 1992-09-29 |
Family
ID=17407618
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000551253A Expired - Fee Related CA1307939C (en) | 1986-11-06 | 1987-11-06 | Method of adjusting bridge circuit of semiconductor |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS63118628A (en) |
| CA (1) | CA1307939C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3915620B2 (en) * | 2002-07-25 | 2007-05-16 | 株式会社デンソー | Semiconductor dynamic quantity sensor |
| JP4578251B2 (en) * | 2005-01-19 | 2010-11-10 | 東京エレクトロン株式会社 | Semiconductor device having microstructure and manufacturing method of microstructure |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS581548B2 (en) * | 1977-03-17 | 1983-01-11 | 株式会社横河電機製作所 | Thin film strain gauge transducer |
| JPS5646594A (en) * | 1979-09-26 | 1981-04-27 | Citizen Watch Co Ltd | Circuit board for electronic clock |
| JPS5786082A (en) * | 1980-11-18 | 1982-05-28 | Seiko Epson Corp | Oscillation circuit for electronic watch |
| JPS5997030A (en) * | 1982-11-26 | 1984-06-04 | Toshiba Corp | Pressure detection hybrid integrated circuit |
| JPS59169184A (en) * | 1983-03-16 | 1984-09-25 | Nec Corp | Manufacture of pressure sensor |
| JPS61232652A (en) * | 1985-04-09 | 1986-10-16 | Matsushita Electric Ind Co Ltd | Adjusting method for electronic circuit |
-
1986
- 1986-11-06 JP JP61264747A patent/JPS63118628A/en active Pending
-
1987
- 1987-11-06 CA CA000551253A patent/CA1307939C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63118628A (en) | 1988-05-23 |
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