JPH11243213A - Manufacture of semiconductor pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To confirm whether positional displaced amount between a pressure introduction hole and a diaphragm is within a tolerable range, without destroying a chip after seat jointing. SOLUTION: A semiconductor pressure sensor in which a plurality of diaphragms 5 are formed by forming a plurality of distortion-sensing elements on the surface of a semiconductor substrate and etching from the rear surface side of each distortion-sensing element and a seat which has a plurality of pressure introducing holes are jointed together. Here, at least one of a semiconductor pressure sensor wafer or a seat is provided with a pattern for confirming the presence of positional displacement between a pressure inlet hole and a diaphragm, and with the semiconductor pressure sensor wafer and the seat jointed together or aligned with each other, the pattern is observed to confirm the presence of positional displacement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor pressure sensor, and more particularly, to an improvement in a process for confirming a displacement between a semiconductor pressure sensor wafer and a pedestal.

[0002]

2. Description of the Related Art FIG. 18 is a sectional view of a semiconductor pressure sensor, and FIGS. 15 to 17 show its manufacturing steps. Semiconductor pressure sensors are mechanical quantity sensors that use the piezoresistance effect of silicon. At the time of manufacturing, as shown in FIG. 15, boron (B) is diffused on a single crystal silicon wafer 1 by using a semiconductor planar technique to form a piezo resistor 2, and as shown in FIG. The concave portion is formed by performing anisotropic etching using an alkaline etchant such as an aqueous potassium hydroxide (KOH) solution to form the diaphragm 5 having a thin portion. Next, FIG.
As shown in FIG. 7, a glass pedestal 7 having a pressure introducing hole 8 is joined to the back surface of the single crystal silicon wafer 1 and cut into a predetermined size, whereby a large number of semiconductor pressure sensor chips are manufactured.

FIG. 19 shows the appearance of the chip viewed from the side of the pressure introducing hole. The glass pedestal 7 is metallized on the surface opposite to the sensor chip with a metal layer 9. As shown in FIG. 19, the glass which becomes the pressure introduction hole 8 from the glass surface or the silicon wafer surface after bonding the metallized glass. It is not possible to check the degree of alignment between the hole and the diaphragm 5, and it is necessary to sacrifice the chip, for example, by destroying the silicon wafer or polishing the glass.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a pressure-introducing hole and a diaphragm which can be used without breaking a chip even after pedestal bonding. It is an object of the present invention to provide a method of manufacturing a semiconductor pressure sensor capable of confirming whether or not the amount of misalignment is within an allowable range.

[0005]

According to the present invention, in order to solve the above-mentioned problems, as shown in FIGS.
A semiconductor pressure sensor wafer 10 having a plurality of strain-sensitive elements 2 formed on the surface of a semiconductor substrate 1 and a plurality of diaphragms 5 formed by performing etching from the back side of each strain-sensitive element 2; In a method of manufacturing a semiconductor pressure sensor by joining a pedestal 7 having
As shown in FIG. 14, at least one of the semiconductor pressure sensor wafer 10 and the pedestal 7 is provided with a pattern for confirming the presence or absence of a displacement between the pressure introducing hole 8 and the diaphragm 5, and the semiconductor pressure sensor wafer 10 and the pedestal 7 are connected to each other. In the joined state or the aligned state, the presence or absence of a position shift is confirmed by observing the pattern. As described above, by providing the pattern for confirming the presence or absence of the displacement between the pressure introducing hole 8 and the diaphragm 5, in the present invention, the pressure introducing hole 5 of the pedestal 7 can be formed without breaking the chip after the pedestal joining. It is possible to confirm whether or not the semiconductor pressure sensor wafer 10 is displaced from the diaphragm 5. It should be noted that the presence or absence of a positional shift may be confirmed at the stage of positioning before pedestal bonding.

[0006]

(Embodiment 1) A method of manufacturing a semiconductor pressure sensor according to Embodiment 1 of the present invention will be described. An oxide film 3 is formed on the entire surface of a single crystal silicon wafer 1 having a thickness of 300 μm and a (100) crystal plane, and a window is formed by a normal photolithography process and an etching process.
A piezoresistive element 2 is formed by an ion implantation step and a diffusion step, and a nitride film 4 is formed on the entire surface of the wafer (FIG. 15).
reference). A window is formed on the surface opposite to the side on which the piezoresistive element 2 is formed by a photolithography process and an etching process, and the silicon in the region to be etched has a desired thickness (for example, 30 μm) using a nitride film 4 as a mask and a KOH solution.
m) is performed until anisotropic etching is performed (see FIG. 16). The nitride film / oxide film on the surface to be etched
₄ Removed by plasma etching, piezoresistive element 2
After forming a contact hole on the surface side on which is formed using a normal photolithography process and an etching process, a wiring 6 is formed by sputtering metal (for example, Al).
The semiconductor pressure sensor wafer 10 is manufactured (see FIG. 17).

[0007] Finally, at least two openings 8a of the metallized glass for the pedestal used for anodic bonding so that (hole diameter of glass for anodic bonding)> (diaphragm opening size after etching). Is formed.
For example, as shown in FIG. 1, when the allowable value of the deviation between the glass pedestal and the semiconductor pressure sensor wafer is 50 μm and the size of the diaphragm (DF) formed on the semiconductor pressure sensor wafer is 2400 μm × 2400 μm, If the hole diameter of the glass of the chip portion is 2500 μm, it can be checked whether the deviation is 50 μm or less.

Further, as shown in FIG. 2, a normal photomask is designed with two chips for mask alignment, so that the glass pedestal corresponding to the chip for mask alignment is mounted on the glass pedestal. It is effective to provide the opening 8a as a pattern for confirmation, since the number of chips obtained per wafer does not decrease. That is,
On the glass pedestal other than the portion corresponding to the chip for mask alignment, pressure introduction holes 8 as shown in FIG. 19 are formed corresponding to the individual pressure sensor chips.

When the pressure sensor is manufactured by the above method, as shown in FIG. 3, if all four sides of the diaphragm 4 can be seen in the glass hole 8a after bonding, the displacement may be within an allowable range. As shown in FIG. 4, if at least one side is not visible at all, the deviation is beyond the allowable range and it can be determined that the wafer is defective.

(Embodiment 2) In Embodiment 2 of the present invention, a plurality of small holes 8b are formed on the side of the glass pedestal 7 to be joined to the semiconductor pressure sensor wafer 10 for confirming the positional deviation, whereby the positional deviation is achieved. This enables quantitative measurement of the amount. For example, as shown in FIG. 5, by opening a plurality of holes having a diameter of 25 μm on the glass pedestal to be bonded for position shift confirmation, 0 to 25 μm, 25 to 50 μm,
Quantitative measurement of the amount of displacement, such as 50 to 75 μm, is possible. In addition, there is an advantage that a decrease in strength is small as compared with the case where a large opening 8a is provided as shown in FIG.

(Embodiment 3) In Embodiment 3 of the present invention, a pattern for confirming the displacement between the semiconductor pressure sensor wafer 10 and the glass pedestal 7 is formed by the nitride film 4 or the oxide film 3. A method for manufacturing the semiconductor pressure sensor according to the present embodiment will be described. An oxide film 3 is formed on the entire surface of a single crystal silicon wafer 1 having a thickness of 300 μm and having a (100) crystal plane, and a window is formed by a normal photolithography step and an etching step. Then, a piezoresistance is formed by an ion implantation step and a diffusion step. The element 2 is manufactured, and a nitride film 4 is formed on the entire surface of the wafer (see FIG. 15). A window is formed on the surface opposite to the side on which the piezoresistive element 2 is formed by a photolithography process and an etching process, and silicon in a region to be etched becomes a desired thickness (for example, 30 μm) with a KOH solution using the nitride film 4 as a mask. Anisotropic etching is performed up to this point (see FIG. 16). Next, on the surface to be etched, the nitride film / oxide film is removed by a photolithography process and an etching process, for example, by CF ₄ plasma etching. At this time, as shown in FIG.
Has a hole diameter of 1300 µm and the allowable amount of misalignment is 50 µm
In this case, the nitride film / oxide film is removed so that a pattern having a diameter of 1200 μm remains. Since a normal photomask is designed with two chips for alignment, if the pattern for confirmation is put in the chip, the number of chips per wafer will not decrease. It is valid.

Further, after forming a contact hole on the surface on which the piezoresistive element 2 is formed by using a usual photolithography process and an etching process, a wiring 6 is formed by sputtering a metal (for example, Al) to form a semiconductor. The pressure sensor wafer 10 is manufactured (see FIG. 17). Finally, anodic bonding of the pedestal metallized glass 7 and the semiconductor pressure sensor wafer 10 is performed. In the anodic bonding, the silicon wafer and the glass pedestal are placed on a hot plate heated to about 300 to 600 ° C., and a DC voltage of about 200 to 2000 V is applied with the silicon wafer side being a positive pole and the glass pedestal side being a minus pole. (Refer to Japanese Patent Application Laid-Open No. 62-21276).

When the pressure sensor is manufactured by the above-described method, as shown in FIG. 7, if at least a part of the pattern of the SiN film 4 for confirming the position shift is not visible in the glass hole 8 after the bonding, Since the displacement is more than the allowable range,
It can be determined that the wafer is defective.

(Embodiment 4) In the embodiment 4 of the present invention, the scale is formed by the pattern for confirming the displacement formed by the nitride film 4 or the oxide film 3 in the above embodiment 3,
The amount of displacement can be checked. For example, as shown in FIG. 8, by patterning a scale of 10 μm intervals with a silicon nitride film (SiN), a quantitative displacement amount measurement of 10 μm can be performed.

(Embodiment 5) In Embodiment 5 of the present invention, a pattern for confirming a position shift is dug into a silicon wafer. A method for manufacturing the semiconductor pressure sensor according to the present embodiment will be described. Forming an oxide film 3 on the entire surface of the single crystal silicon wafer 1 having a thickness of 300 μm and a (100) crystal plane;
After opening a window by a usual photolithography process and an etching process, a piezoresistive element 2 is manufactured by an ion implantation process and a diffusion process, and a nitride film 4 is formed on the entire surface of the wafer.
Is formed (see FIG. 15). A window is formed in the nitride film 4 by a photolithography step and an etching step on the surface opposite to the side on which the piezoresistive element 2 is manufactured. At this time, a pattern that satisfies (hole diameter of glass for performing anodic bonding)> (diaphragm opening size after etching) is formed in at least two places of the mask used in the photolithography process. Next, KO is performed using this nitride film 4 as a mask.
Anisotropic etching is performed using H solution until the silicon in the region to be etched has a desired thickness (for example, 30 μm). For example, the allowable value of the displacement between the glass pedestal and the silicon wafer is 50 μm, and the hole diameter of the bonding glass is 1300 μm.
In the case of m, as shown in FIG. 9, if the mask size is set to 1200 μm × 1200 μm, the diaphragm opening size does not change even after etching, so that it is possible to confirm whether the deviation is 50 μm or less. Also,
Since a normal photomask is designed with two chips for alignment, if the pattern for confirmation is put in the chip, the number of chips per wafer will not decrease. It is valid.

Next, on the surface to be etched, the nitride film / oxide film is removed by, for example, CF ₄ plasma etching by a photolithography process and an etching process, and a normal photolithography process is performed on the surface on which the piezoresistive element 2 is formed. After forming a contact hole by using a process and an etching process, a metal (for example, Al) is sputtered to form a wiring 6, and a semiconductor pressure sensor wafer 10 is manufactured. Finally, anodic bonding of the pedestal metallized glass 7 and the silicon wafer 10 is performed.

When the pressure sensor is manufactured by the above method, if all four sides of the diaphragm can be seen in the glass hole after bonding (FIG. 10), it can be understood that the displacement is within the allowable range, and at least 1 If the side is not visible at all (FIG. 11), the displacement is more than the allowable range.
It can be determined that the wafer is defective.

(Embodiment 6) In Embodiment 6 of the present invention, as a pattern for confirming the positional deviation between the wafer 10 and the pedestal 7, as shown in FIG. A plurality of (10 μm × 10 μm) diaphragm patterns are arranged. In this way, it is possible to quantitatively measure the amount of displacement between the wafer and the pedestal in units of 10 μm.

(Embodiment 7) In Embodiment 7 of the present invention, the end point of etching can be determined by adjusting the size of the pattern for confirming the positional deviation between the wafer 10 and the pedestal 7. For example, as shown in FIG.
μm × 326 μm), B pattern (354 μm × 354
If the C pattern (382 μm × 382 μm) is used as a pattern for confirming the positional deviation between the wafer 10 and the pedestal 7, as shown in FIG.
When the pattern A is etched, the etching of the pattern A is stopped, and when the etching of 250 μm is performed, the etching of the pattern B is stopped. That is, in order to set the amount of etching of the diaphragm to 250 μm, it is only necessary to end the etching when the etching of the B pattern is stopped.

[0020]

According to the first, fourth or sixth aspect of the present invention, at least one of the semiconductor pressure sensor wafer and the pedestal is provided with a pattern for confirming whether or not there is a displacement between the pressure introducing hole and the diaphragm. In the state where the semiconductor pressure sensor wafer and the pedestal are bonded or aligned, by observing the pattern to check for the presence or absence of a displacement, the pressure introduction hole of the pedestal and the semiconductor without breaking the chip after the pedestal bonding. It is possible to confirm the presence / absence of displacement of the pressure sensor wafer from the diaphragm. In addition, since a normal photomask is designed with two chips for positioning, if a pattern for confirming the position shift is put in the chip, the number of chips to be removed per wafer also decreases. It is effective because there is no.

According to the second, third, or seventh aspect of the present invention, the arrangement of a plurality of confirmation patterns has an effect that the amount of displacement can be quantitatively measured.
According to the invention, the scale is formed by the check pattern, so that the amount of positional deviation can be quantitatively and finely measured. Furthermore, according to the invention of claim 8, by adjusting the size of the confirmation pattern, it is possible to determine the end point of the etching when forming the diaphragm.

[Brief description of the drawings]

FIG. 1 is a front view illustrating an example of a glass pattern according to a first embodiment of the present invention.

FIG. 2 is a front view illustrating an example of a mask pattern according to the first embodiment of the present invention.

FIG. 3 is a front view showing a case where the displacement according to the first embodiment of the present invention is within an allowable range.

FIG. 4 is a front view showing a case where the positional deviation of the first embodiment of the present invention is equal to or larger than an allowable range.

FIG. 5 is a front view illustrating an example of a glass pattern according to a second embodiment of the present invention.

FIG. 6 is a front view showing an example of a nitride film pattern according to a third embodiment of the present invention.

FIG. 7 is a front view illustrating a case where a positional shift is equal to or larger than an allowable range according to a third embodiment of the present invention.

FIG. 8 is a front view showing an example of a nitride film pattern according to a fourth embodiment of the present invention.

FIG. 9 is a front view illustrating an example of a diaphragm pattern according to a fifth embodiment of the present invention.

FIG. 10 is a front view illustrating a case where a position shift is within an allowable range according to a fifth embodiment of the present invention.

FIG. 11 is a front view illustrating a case where a positional shift is equal to or larger than an allowable range according to a fifth embodiment of the present invention.

FIG. 12 is a front view illustrating an example of a diaphragm pattern according to a sixth embodiment of the present invention.

FIG. 13 is a front view illustrating an example of a diaphragm pattern according to a seventh embodiment of the present invention.

FIG. 14 is a sectional view showing a sectional structure of a diaphragm according to a seventh embodiment of the present invention.

FIG. 15 is a cross-sectional view showing a first stage of a manufacturing process of a conventional semiconductor pressure sensor.

FIG. 16 is a cross-sectional view showing a second stage of the manufacturing process of the conventional semiconductor pressure sensor.

FIG. 17 is a cross-sectional view showing a third stage of the manufacturing process of the conventional semiconductor pressure sensor.

FIG. 18 is a sectional view of a conventional semiconductor pressure sensor.

FIG. 19 is a front view of a conventional semiconductor pressure sensor.

[Explanation of symbols]

 5 Diaphragm 8 Pressure introduction hole

Claims (8)

[Claims] 1. A semiconductor pressure sensor wafer comprising: a plurality of strain-sensitive elements formed on a front surface of a semiconductor substrate; and a plurality of diaphragms formed by etching from the back side of each strain-sensitive element; and a plurality of pressure introduction holes. In a method of manufacturing a semiconductor pressure sensor by bonding a pedestal having at least one of a semiconductor pressure sensor wafer and a pedestal, a semiconductor pressure sensor wafer is provided with a pattern for confirming the presence or absence of a displacement between a pressure introduction hole and a diaphragm. A method of manufacturing a semiconductor pressure sensor, comprising: observing the pattern in a state in which the substrate and the pedestal are joined or in a state where the pedestal is aligned, and confirming the presence or absence of a displacement. 2. The method for manufacturing a semiconductor pressure sensor according to claim 1, wherein a plurality of patterns for confirming a position shift are provided. 3. The method of manufacturing a semiconductor pressure sensor according to claim 2, wherein a plurality of diameter pressure introducing holes are provided on the pedestal as a pattern for confirming the positional deviation. 4. The method for manufacturing a semiconductor pressure sensor according to claim 1, wherein a pattern for confirming a position shift is formed of a nitride film or an oxide film. 5. The method for manufacturing a semiconductor pressure sensor according to claim 4, wherein a scale for confirming the amount of misalignment is formed by a misalignment confirmation pattern formed of a nitride film or an oxide film. 6. The method for manufacturing a semiconductor pressure sensor according to claim 1, wherein a pattern for confirming a position shift is dug in a silicon wafer. 7. The method for manufacturing a semiconductor pressure sensor according to claim 6, wherein a plurality of misregistration confirmation patterns dug into the silicon wafer are provided. 8. The method of manufacturing a semiconductor pressure sensor according to claim 6, wherein the size of the pattern for confirming the positional deviation is adjusted so that the etching end point of the diaphragm can be confirmed.