JPH09101218A - Manufacture of semiconductor sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a silicon water against damage in anode bonding. SOLUTION: A silicon wafer 21 is provided with a recess 11 for each chip thereof. A glass base 22 is composed of aluminosilicate glass and a hole 23 is extending downward from the surface being bonded to the silicon wafer 21. The silicon wafer 21 is abutted against the glass base 22 and then they are anode-bonded (first step). More specifically, the silicon wafer 21 and the glass base 22 are arranged between upper and lower electrodes 25, 26 and anode- bonded under high temperature and high voltage conditions. Since the hole 23 is closed partially, discharge is retarded. After finishing the anode bonding, rear surface of glass base 22 is polished so that the upper surface communicates with the rear surface through the hole 23 thus making a pressure introduction hole (second step) Finally, the silicon wafer 21 and the glass base 22 are diced into each chip.

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 sensor in which a silicon wafer and a glass pedestal are anodically bonded.

[0002]

2. Description of the Related Art As a conventional semiconductor sensor, for example, a semiconductor pressure sensor, a glass pedestal having a pressure introducing hole, a thin wall portion formed by a recess serving as a diaphragm, and a pressure receiving chamber communicating with the pressure introducing hole in the recess. And a pressure-sensitive silicon substrate (silicon wafer). In the manufacturing process of such a semiconductor pressure sensor, as shown in FIG. 11, the silicon wafer 51 and the glass pedestal 52 are anodically bonded by applying a high voltage between the upper electrode 53 and the lower electrode 54. The reference numeral 55 indicates a diaphragm,
Reference numeral 56 indicates a pressure introducing hole.

[0003]

However, when the above-mentioned anodic bonding is performed, there is a risk that the silicon wafer 51 is damaged due to a discharge phenomenon occurring in the pressure introducing hole 56 of the glass pedestal 52. This inconvenience affects the yield rate and man-hour cost of the product and is reflected in the price of the semiconductor sensor, so it was necessary to eliminate it. In particular, when the glass pedestal is made of aluminosilicate glass (for example, Japanese Patent Application Laid-Open No. 4-83733), the above-mentioned inconvenience tends to occur.

The present invention has been made in view of the above problems, and an object thereof is to provide a method for manufacturing a semiconductor sensor capable of preventing damage to a silicon wafer during anodic bonding. It is in.

[0005]

In the present invention, as a first step, the silicon wafer and the glass pedestal are anodically bonded in a state in which the through hole of the glass pedestal is blocked. As the second step, the blocking portion of the through hole is removed after the anodic bonding. That is, according to the conventional method of manufacturing a semiconductor sensor, discharge may occur in the through hole during anodic bonding, and the silicon wafer may be damaged due to this discharge. On the other hand, according to the manufacturing method of the present invention, since the anodic bonding is performed in the state where the through hole is closed, damage to the silicon wafer due to discharge can be avoided.

As a manufacturing method thereof, the forms as described in claims 2 to 4 are conceivable, and in any case, the damage of the silicon wafer due to the discharge can be similarly prevented. Further, the present invention is particularly effective when the glass pedestal is formed of aluminosilicate glass as described in claim 5.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention embodied in a semiconductor pressure sensor will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a commonly used semiconductor pressure sensor. In the semiconductor pressure sensor 1 of FIG. 1, the frame body 2, the port case 3 and the lid body 4 are adhered in an airtight state, and the housing 5 is constituted by these members. A protrusion 6 for mounting the stem is formed inside the housing 5, and the protrusion 6 is made of metal (for example,
42 alloy) stem 7 is adhesively fixed.

A glass pedestal 8 is die-bonded onto the stem 7, and a chip-shaped pressure-sensitive silicon substrate 9 is bonded onto the glass pedestal 8. More specifically, as shown in FIG. 2, a pressure introducing hole 10 is formed in the glass pedestal 8. Further, a concave portion 11 is formed in the pressure-sensitive silicon substrate 9, and a thin portion formed by the concave portion 11 serves as a diaphragm 12. On the surface of the diaphragm 12,
A piezoresistive layer (not shown) is formed by impurity diffusion, and this diaphragm 12 serves as a detection portion. A signal processing circuit (not shown) having a resistance for adjustment is integrated and formed in the thick portion other than the diaphragm. A pressure receiving chamber 13 is formed inside the recess 11 of the pressure-sensitive silicon substrate 9, and the pressure receiving chamber 13 and the pressure introducing hole 10 of the glass pedestal 8 are communicated with each other.

On the other hand, in FIG. 1, a shell 14 is welded on the stem 7 so as to surround the pressure-sensitive silicon substrate 9,
The pressure sensitive silicon substrate 9 is protected from the external environment. In the case of an absolute pressure sensor, the shell 14 is evacuated to serve as a pressure reference chamber.

Further, the pressure-sensitive silicon substrate 9 has a stem lead 1 penetrating the stem 7 with a bonding wire 15.
6, and the stem lead 16 is electrically connected to the housing lead 17 penetrating the housing 5. A vacuum hose 18 is connected to the port case 3.

Therefore, the detected pressure is the vacuum hose 18
Through hole 7a of stem 7 and pressure introduction hole 1 of glass pedestal 8
It is transmitted to the diaphragm 12 of the pressure-sensitive silicon substrate 9 via 0, and the diaphragm 12 is deformed according to the pressure. Then, the resistance value of the piezoresistive layer changes according to the deformation of the diaphragm 12, and the change in the resistance value is extracted as an electric signal.

The semiconductor pressure sensor 1 having such a structure is used as, for example, an intake pressure sensor for detecting an intake negative pressure of an automobile engine, and the detection result of the sensor is used for fuel injection control and ignition timing control of the engine. Reflected in.

Next, a main part of the method for manufacturing the semiconductor pressure sensor 1 will be described with reference to FIGS. In FIG. 3, a silicon wafer 21 has a large number of pressure-sensitive silicon substrates 9, and
A concave portion 11 is formed in each substrate 1 on the substrate 1. The glass pedestal 22 has a flat plate shape, and has a hole portion 23 extending downward from a joint surface with the silicon wafer 21. That is, the hole 2
3 is opened only on one surface (upper surface in the figure), and the silicon wafer 2
1 corresponds to each recess 11. When the silicon wafer 21 and the glass pedestal 22 are brought into contact with each other, the silicon wafer 21
The recess 11 and the opening of the hole 23 of the glass pedestal 22 communicate with each other.

Then, the silicon wafer 21 and the glass pedestal 22 are brought into contact with each other, and both members are anodically bonded (first step). That is, as shown in FIG.
The glass pedestal 22 is disposed between the upper electrode 25 and the lower electrode 26, and anodic bonding is performed under the conditions of high temperature and high voltage. Reference numeral 27 is a switch for turning on / off the power supply, and reference numeral 28 is a DC power supply. Specific conditions for anodic bonding include temperature = 350 ° C. and voltage = 400-
It is 800 volts and the upper electrode 25 has a weight of about 500 grams.

FIG. 5 shows a silicon wafer 21 after anodic bonding.
And the glass pedestal 22. From this state, the glass pedestal 2 is shown.
The back surface of No. 2 is polished to obtain the state of FIG. That is, FIG.
In FIG. 6, the hole 23 is made to penetrate through both upper and lower surfaces, and the pressure introducing hole 1
0 is formed (second step). After that, the silicon wafer 21 and the glass pedestal 22 are diced and cut for each substrate 9.

According to the above-described embodiment, it is possible to obtain the effect of preventing damage to the silicon wafer 21 due to discharge during anodic bonding. That is, in the conventional process shown in FIG. 11, discharge may occur between the lower electrode 54 and the silicon wafer 51, and the silicon wafer 51 may be damaged. On the other hand, according to the present embodiment, since the discharge path is cut off, the problem that the silicon wafer is damaged without causing the discharge can be solved.

In particular, when the aluminosilicate glass is used, there is a tendency that the above-mentioned inconvenience due to the discharge tends to be caused, but by using the manufacturing method of this embodiment, the semiconductor pressure sensor can be manufactured without any trouble. can do.
Further, by forming the glass pedestal from aluminosilicate glass, the thermal expansion coefficient of the pressure-sensitive silicon substrate and the glass pedestal can be made approximately the same, and thermal stress is relieved to provide a highly accurate semiconductor pressure sensor. can do.

7 and 8 are cross-sectional views showing a method of manufacturing a semiconductor pressure sensor according to another embodiment, and the object of the present invention can be achieved by the method shown. That is, in FIG. 7, the plate-shaped glass pedestal 22 without the hole 23 (see FIG. 3) is used. In such a case, the recess 11 is formed after anodic bonding.
A pressure introducing hole 10 (indicated by a broken line) communicating with is formed.

Further, in FIG. 8, pressure introducing holes 10 penetrating the upper and lower surfaces of the glass pedestal 22 are formed in advance,
At the time of anodic bonding, a thin glass plate 29 is laid under the glass pedestal 22. The material of the glass plate 29 is the same as that of the glass pedestal 22. Then, as shown in the drawing, the silicon wafer 21, the glass pedestal 22 and the glass plate 29 are stacked, and in this state, anodic bonding is performed by the upper electrode 25 and the lower electrode 26. After the anodic bonding, the glass plate 29 is removed. This Figure 8
In the method shown in (1), the polishing process and the perforating process of the glass pedestal 22 are unnecessary.

On the other hand, the present invention can be applied to a method of manufacturing a semiconductor acceleration sensor as well as a semiconductor pressure sensor. 9 is a plan view showing a main part of the semiconductor acceleration sensor, and FIG. 10 is a sectional view taken along line XX of FIG.

In the semiconductor acceleration sensor 31 shown in FIGS. 9 and 10, a silicon substrate 33 is arranged on a glass pedestal 32 made of aluminosilicate glass. The silicon substrate 33 is formed with a first supporting portion 34 as an outer shell, and a U-shaped second supporting portion 36 is connected to the inside of the first supporting portion 34 via a connecting portion 35. There is. Further, the second support portion 36 includes four thin movable portions 37, 38, 39,
A thick-walled substantially square-shaped weight portion 41 is connected via 40. The thickness of the movable portions 37, 38, 39, 40 is about 5 μm, and a pair of piezoresistive layers 42a, 42b, 43a, 43b, 44a, 44b, and
45a and 45b are formed. The movable part 37-
40 and the weight part 41 correspond to a detection part. FIG.
In the above, a through hole 46 is formed in the glass pedestal 32 so that the glass pedestal 32 does not come into contact when the weight portion 41 is displaced due to acceleration.

Even in the semiconductor acceleration sensor 31 having such a structure, the through hole 4 of the glass pedestal 32 is manufactured during the manufacturing process.
6 is closed, and in this state, the glass pedestal 32 and the silicon substrate 33 (silicon wafer) are anodically bonded. More specifically, as described in the semiconductor pressure sensor, the glass pedestal 32 is provided with a hole (not shown) that opens only in the bonding surface with the silicon substrate 33 (silicon wafer), and the glass pedestal 32 is bonded after anodic bonding. The bottom surface is polished to form the through hole 46. On the other hand, a glass pedestal 32 having a through hole 46 formed therein is prepared, and a glass plate is laid under the glass pedestal 32.
Then, in that state, the upper electrode and the lower electrode may be installed to perform anodic bonding, and then the glass plate may be removed.

In any of the above-mentioned forms, the discharge passage during anodic bonding is blocked, and as a result, damage to the silicon substrate 33 (silicon wafer) due to discharge can be suppressed.

The present invention can be embodied in the following modes other than the above embodiment. Although the glass pedestals 8 (22) and 32 are formed of aluminosilicate glass in the above embodiment, they may be changed to borosilicate glass (Pyrex glass), for example. Also in this case, it is possible to suppress discharge during anodic bonding and prevent damage to the silicon wafer.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the configuration of a general semiconductor pressure sensor.

FIG. 2 is a cross-sectional view showing a pressure-sensitive silicon substrate and a glass pedestal.

FIG. 3 is a cross-sectional view showing the manufacturing process of the semiconductor pressure sensor.

FIG. 4 is a cross-sectional view showing the manufacturing process of the semiconductor pressure sensor.

FIG. 5 is a cross-sectional view showing the manufacturing process of the semiconductor pressure sensor.

FIG. 6 is a cross-sectional view showing the manufacturing process of the semiconductor pressure sensor.

FIG. 7 is a cross-sectional view showing a manufacturing process of a semiconductor pressure sensor according to another embodiment.

FIG. 8 is a sectional view showing a manufacturing process of a semiconductor pressure sensor according to another embodiment.

FIG. 9 is a plan view showing a main part of a semiconductor acceleration sensor.

FIG. 10 is a sectional view taken along line XX of FIG. 9;

FIG. 11 is a cross-sectional view showing the manufacturing process of the semiconductor pressure sensor in the conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor pressure sensor, 8 ... Glass pedestal, 9 ... Pressure-sensitive silicon substrate, 10 ... Pressure introduction hole, 12 ... Diaphragm as a detection part, 21 ... Silicon wafer, 23 ... Hole part, 2
9 ... Glass plate, 31 ... Semiconductor acceleration sensor, 32 ... Glass pedestal, 33 ... Silicon substrate, 37-40 ... Movable part as detection part, 41 ... Weight part as detection part, 46 ... Through hole.

Claims (5)

[Claims] 1. A method of manufacturing a semiconductor sensor, comprising: a glass pedestal having a through hole; and a silicon substrate bonded to the glass pedestal and having a detection section facing the through hole. A first step of anodic bonding the silicon wafer and the glass pedestal with the through hole blocked, and a second step of removing the blocked part of the through hole after the anodic bonding in the first step. A method for manufacturing a semiconductor sensor, which comprises: 2. The glass pedestal is preliminarily formed with a hole having a predetermined depth and extending from a bonding surface with the silicon wafer, and in the second step, the bottom surface of the glass pedestal is polished. The method for manufacturing a semiconductor sensor according to claim 1, wherein the hole is penetrated. 3. In the first step, the silicon wafer and a plate-shaped glass pedestal are anodically bonded, and in the second step, a through hole is formed in the glass pedestal so as to communicate with the detection portion of the silicon wafer. The method for manufacturing a semiconductor sensor according to claim 1, wherein the semiconductor sensor is drilled. 4. In the first step, the silicon wafer, a glass pedestal in which a through hole is formed in advance, and a glass plate are superposed in that order to perform anodic bonding, and in the second step, the glass plate Claim 1 which removes
A method for manufacturing the semiconductor sensor according to 1. 5. The method of manufacturing a semiconductor sensor according to claim 1, wherein the glass pedestal is aluminosilicate glass.