JPH0621483A - Pressure regulator for integrated pressure sensor - Google Patents

Abstract

PURPOSE:To provide a pressure regulator for an integrated pressure sensor in which air tightness is kept without use of a press member and an output adjustment is ensured in a wafer state. CONSTITUTION:A silicon wafer 1 of an integrated pressure sensor includes a signal processor circuit having an adjustment resistor for each chip, a thin- walled diaphragm 2 for each chip, and a piezoelectric resistance layer for each chip all formed thereon. On a pressure setting stage 8 there are formed pressure regulator passages 9a, 9b, 9c for the stage for regulating pressure applied to the diaphragm 2. A groove 12 is formed in the upper surface of the pressure setting stage 8, which groove opposes to the lower surface of the extended periphery of a glass pedestal 6 and surrounds the external periphery of the glass pedestal 6. A permanent magnet 13 is fixed in the groove 12, and the groove 12 in filled with a magnetic fluid 14 to keep the pressure setting stage 8 and the glass pedestal 6 in air tightness with the magnetic fluid 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure adjusting device for an integrated pressure sensor, and more particularly to a pressure adjusting device for an integrated pressure sensor that applies a predetermined pressure to the wafer in order to adjust the output in the wafer state. It is about.

[0002]

2. Description of the Related Art Recently, there has been a demand for functional trimming of a semiconductor pressure sensor in a wafer state in order to reduce costs and improve productivity. Therefore, output adjustment (trimming) is performed by applying a predetermined pressure to the integrated pressure sensor in a wafer state. FIG. 5 shows a pressure adjusting device for an integrated pressure sensor for this purpose. A silicon wafer 32 bonded to a glass pedestal 31 is provided on the upper surface of the pressure setting stage 30.
Are arranged, and the outer peripheral portion of the silicon wafer 32 is pressed by the pressing member 33. The O-rings 34 and 35 hermetically maintain the space between the pressing member 33 and the pressure setting stage 30 and between the pressing member 33 and the silicon wafer 32. The pressure of the vacuum pump 36 can be applied to each diaphragm of the silicon wafer 32 through the stage pressure adjusting passage 37 and the pedestal pressure adjusting passage 38. Sensor output adjustment (pressure sensitivity adjustment)
At that time, the atmospheric pressure and a predetermined negative pressure were applied to each diaphragm, and the prober 39 was used to trim the resistors by the laser device 40.

[0003]

However, since the pressing member 33 covers the silicon wafer 32, it is difficult to probe the chip on the outer periphery of the silicon wafer 32. Further, it takes a lot of time to attach the pressing member 33 and wear of the O-rings 34 and 35 deteriorates the airtightness.

SUMMARY OF THE INVENTION An object of the present invention is to provide a pressure adjusting device for an integrated pressure sensor which can be kept airtight without using a pressing member and can adjust the output in a wafer state.

[0005]

SUMMARY OF THE INVENTION According to the present invention, there is provided an integrated pressure device, in which a signal processing circuit having an adjusting resistor for each chip, a thin diaphragm for each chip, and a piezoresistive layer for each chip are formed on a silicon wafer. A pressure setting stage for adjusting the output of the sensor, the pressure setting stage having a stage pressure adjusting passage for adjusting the pressure applied to the diaphragm, on which the silicon wafer or a pedestal to which the silicon wafer is bonded is placed. And a groove portion formed so as to face the lower surface of the outer peripheral portion of the silicon wafer or the pedestal on the upper surface of the pressure setting stage and surround the outer peripheral portion of the silicon wafer or the pedestal, and a magnet fixed in the groove portion. And a magnetic fluid that is filled in the groove and has a magnetic fluid that holds the pressure setting stage and the silicon wafer or the base airtight. The pressure regulating device for capacitors in which the gist thereof.

[0006]

The groove is formed so as to surround the outer peripheral portion of the silicon wafer or the pedestal on the upper surface of the pressure setting stage, the magnet is fixed in the groove, and the magnetic fluid is filled therein. The magnetic fluid maintains airtightness between the pressure setting stage and the silicon wafer or the pedestal. Then, in this magnetic fluid sealed state, the pressure applied to the diaphragm is adjusted through the stage pressure adjusting passage of the pressure setting stage, and the adjusting resistor of the signal processing circuit is trimmed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall configuration of a pressure adjusting device for an integrated pressure sensor. A thin diaphragm 2 for each chip is formed on a silicon wafer 1. As shown in FIG. 2, a piezoresistive layer (gauge resistor) 3 for each chip and a signal processing circuit 5 having an adjusting resistor (thin film resistor) 4 for each chip are formed on the silicon wafer 1. ing. That is, as shown in FIG. 2, the central portion is thinly processed to form the diaphragm 2, the piezoresistive layer 3 is formed on the diaphragm 2 by impurity diffusion, and the thick portion other than the diaphragm 2 is used for adjustment. A signal processing circuit 5 having a resistor 4 is integrated and formed. Then, the signal processing circuit 5 performs processing such as amplification on the signal generated from the piezoresistive layer 3.

The glass pedestal 6 shown in FIG. 1 is provided with a number of pedestal pressure adjusting passages 7 corresponding to the diaphragm 2 of the silicon wafer 1. One end of the passage 7 is opened on the upper surface and the other end is opened on the lower surface. is doing. Then, as shown in FIG. 1, the silicon wafer 1 is anodically bonded onto the glass pedestal 6.

The pressure setting stage 8 is made of a non-magnetic resin. The pressure setting stage 8 is provided with stage pressure adjusting passages 9a, 9b, 9c. One end of the stage pressure adjusting passage 9c is open to the lower surface and the other end is the passage 9c.
The stage pressure adjusting passage 9a communicates with a, and a large number of passages 9b branch off. The other end of the stage pressure adjusting passage 9b is opened on the upper surface of the pressure setting stage 8, and each opening is opposed to one end of the pedestal pressure adjusting passage 7 of the glass pedestal 6. The stage pressure adjusting passage 9c is connected to the vacuum pump 10. Then, by the vacuum pump 10, the stage pressure adjusting passages 9a, 9b,
9c is made a negative pressure. The stage pressure adjusting passage 9c
A pressure gauge 11 is connected to.

The glass pedestal 6 to which the silicon wafer 1 is bonded is placed on the pressure setting stage 8. On the other hand, the groove 1 is formed on the upper surface of the pressure setting stage 8.
2 is formed, and the groove portion 12 is formed in a circular shape so as to face the lower surface of the outer peripheral portion of the glass pedestal 6 and surround the outer peripheral portion of the pedestal 6. A permanent magnet 13 is fixed to the bottom of the groove 12 over the entire length. The groove 12 is filled with the magnetic fluid 14. The magnetic fluid 14 is made by dispersing fine iron particles in oil and has a viscosity of about 10,000 cSt (centistokes).

Next, the operation of the pressure adjusting device for the integrated pressure sensor thus configured will be described. With the magnetic fluid 14 filled in the groove portion 12, on the pressure setting stage 8,
The glass pedestal 6 to which the silicon wafer 1 is bonded is placed.
At this time, the magnetic fluid 14 keeps the lower surface of the glass pedestal 6 and the upper surface of the pressure setting stage 8 airtight.

Then, in this state, the pressure sensitivity is adjusted for each chip. In other words, the resistance value is adjusted by irradiating the adjusting resistor 4 with the laser beam from the laser device 17 while applying the prober (needle) 16 to the probing pad 15 (shown in FIG. 2). This adjustment is performed by applying the atmospheric pressure and a predetermined negative pressure (-758 mmHg gauge pressure) to the diaphragm 2 using the vacuum pump 10 and the pressure gauge 11.

At the time of applying the negative pressure, as shown in FIG. 3, the magnetic fluid 14 closes and seals a minute gap between the glass pedestal 6 and the pressure setting stage 8. At this time, the magnetic fluid 14 does not pass through the gap due to its own viscosity and the attractive force of the permanent magnet 13 to flow into the stage pressure adjusting passage 9b.

The silicon wafer 1 and the glass pedestal 6 which have been subjected to the pressure sensitivity adjustment in this manner are removed from the pressure setting stage 8. At this time, the permanent magnet 13 causes the magnetic fluid 14
Is pulled, the magnetic fluid 14 is attached to the glass pedestal 6
The amount attached to is minimal.

After that, the silicon wafer 1 and the glass pedestal 6 are diced and cut into chips. As described above, in this embodiment, the groove 12 is formed on the upper surface of the pressure setting stage 8.
The groove 12 faces the lower surface of the outer peripheral portion of the glass pedestal 6 and surrounds the outer peripheral portion of the glass pedestal 6,
The permanent magnet 13 was fixed in the groove portion 12, the magnetic fluid 14 was filled in the groove portion 12, and the magnetic fluid 14 kept the pressure setting stage 8 and the glass pedestal 6 airtight. Therefore, airtightness can be maintained without using the pressing member 33 and the O-rings 34 and 35 shown in FIG. 5, and output adjustment can be performed in a wafer state. That is, since the pressing member 33 is not provided on the upper surface of the silicon wafer 1, the outermost peripheral portion of the silicon wafer 1 can be probed. Further, since the O-ring is not used, there is no wear of the O-ring, and maintenance can be performed only by periodically replenishing the magnetic fluid 14. Furthermore, high airtightness can be achieved with a simple setting.

The present invention is not limited to the above embodiment, and may be applied to the case where the silicon wafer 1 having no glass pedestal bonded thereto is trimmed as shown in FIG. 4, for example.

[0017]

As described above in detail, according to the present invention,
It is possible to maintain airtightness without using a pressing member, and to exert an excellent effect that output adjustment can be performed in a wafer state.

[Brief description of drawings]

FIG. 1 is a sectional view of a pressure adjusting device for an integrated pressure sensor according to an embodiment.

FIG. 2 is a perspective view showing an integrated pressure sensor made into a chip.

FIG. 3 is an enlarged view of a main part of a pressure adjusting device for an integrated pressure sensor.

FIG. 4 is a cross-sectional view of another example pressure adjusting device for an integrated pressure sensor.

FIG. 5 is a sectional view of a conventional pressure adjusting device for an integrated pressure sensor.

[Explanation of symbols]

 1 Silicon Wafer 2 Diaphragm 3 Piezoresistive Layer 4 Adjustment Resistor 5 Signal Processing Circuit 6 Glass Pedestal 8 Pressure Setting Stage 9a, 9b, 9c Stage Pressure Adjustment Passage 12 Groove 13 Permanent Magnet 14 Magnetic Fluid

Claims (1)

[Claims] 1. An integrated pressure sensor for adjusting the output of a signal processing circuit having an adjusting resistor for each chip, a thin diaphragm for each chip, and a piezoresistive layer for each chip formed on a silicon wafer. A silicon wafer or a pedestal to which the silicon wafer is bonded is placed, a pressure setting stage having a stage pressure adjusting passage for adjusting the pressure applied to the diaphragm, and the pressure setting stage upper surface. Groove facing the lower surface of the outer peripheral portion of the silicon wafer or the pedestal and surrounding the outer peripheral portion of the silicon wafer or the pedestal, a magnet fixed in the groove portion, the groove portion is filled. For an integrated pressure sensor, characterized by comprising a magnetic fluid for hermetically holding the pressure setting stage and the silicon wafer or pedestal Force adjustment device.