JPH0783707A - Manufacture of thin film semiconductor sensor chip - Google Patents

Abstract

PURPOSE:To prevent possible breakage at a thin film part by filling a space part with a reinforcing material in cutting with a dicing device to integrate the thin film part facing the space part with the reinforcing material. CONSTITUTION:In the dividing of a plurality of thin film semiconductors 18 formed on a semiconductor substrate wafer 19 into individual thin film semiconductor sensor chips 1, the following steps are performed. A step of filling a space part 9 disposed for each of the thin film semiconductor sensors 18 with a reinforcing material 20, a step of cutting a semiconductor substrate wafer 1 filled with the reinforcing material 20 with a dicing device into the individual thin film semiconductor sensor chips 1 and a step of removing the reinforcing material after the cutting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in, for example, a flow sensor, a pressure sensor, a gas sensor, etc., and a thin film semiconductor sensor in which a sensor circuit element as a detection portion of these sensors is formed by micromachining processing on a semiconductor substrate. The present invention relates to a chip manufacturing method.

[0002]

2. Description of the Related Art A flow sensor for detecting the flow rate of a minute fluid, a pressure sensor for generating an output corresponding to the ambient pressure,
And a thin film semiconductor sensor chip that is used in a gas sensor that produces an output in response to a gas of a predetermined type, and that has a sensor circuit element as a detection portion of the sensor that is micromachined on a semiconductor substrate. In order to perform thermal insulation between the semiconductor substrate and the thin film portion of the element and the portion where the sensor circuit element is provided, the thin film portion of the portion where the sensor circuit element is provided is formed in a bridge shape with respect to the semiconductor substrate. In some semiconductor substrates, a space is provided. A thin film semiconductor sensor having such a configuration is generally formed by batching a plurality of thin film semiconductor sensors on a semiconductor substrate wafer by micromachining. A manufacturing method has been adopted in which the thin film semiconductor sensor is divided into individual thin film semiconductor sensor chips.

[0003]

However, in the above-described manufacturing method, since the semiconductor substrate wafer is cut by the dicing device and divided into the individual thin film semiconductor sensor chips, the impact (mechanical vibration, dicing) generated at that time is cut. There has been a problem that the thin film portion facing the space is damaged due to the impact of water for cooling the cutting edge of the device).

The present invention solves the above problems and provides a method of manufacturing a thin film semiconductor sensor chip capable of preventing the occurrence of damage in a thin film portion facing a space even when a semiconductor substrate wafer is cut using a dicing device. Is to provide.

[0005]

In order to achieve the above object, the present invention provides a sensor circuit element in a thin film portion formed on a semiconductor substrate, and heats the thin film portion in the portion where the sensor circuit element is provided. A thin-film semiconductor sensor having a space between the thin-film portion and the semiconductor substrate below the thin-film portion is formed on one semiconductor substrate wafer so as to form a bridge with the semiconductor substrate for static insulation. In the method of manufacturing a thin film semiconductor sensor chip, a plurality of thin film semiconductor sensors are collectively formed, and one semiconductor substrate wafer on which the plurality of thin film semiconductor sensors are collectively formed is cut by a dicing device and divided into individual thin film semiconductor sensor chips, When dividing a plurality of thin film semiconductor sensors collectively formed on one semiconductor substrate wafer into individual thin film semiconductor sensor chips,
A first step of filling a reinforcing material in the space of each thin film semiconductor sensor provided for each thin film semiconductor sensor;
A second step of cutting the semiconductor substrate wafer filled with the reinforcement into individual thin film semiconductor sensor chips by a dicing device, and a third step of removing the reinforcement from the space of each thin film semiconductor sensor chip after the cutting. It is characterized by going through the process of.

[0006]

According to the present invention, after filling the space provided for each thin film semiconductor sensor with a reinforcement, the semiconductor substrate wafer filled with the reinforcement is cut into individual thin film semiconductor sensor chips by a dicing device. Then, the reinforcing material is removed after cutting. Therefore, at the time of cutting by the dicing device, since the space portion is filled with the reinforcing material, the thin film portion facing the space portion is integrated with the reinforcing material, so that the thin film portion can be prevented from being damaged.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partially enlarged plan view showing one thin film semiconductor sensor among a plurality of thin film semiconductor sensors formed on a semiconductor substrate wafer by a micromachining process. The thin film semiconductor sensor in this embodiment is configured to be used as a flow rate sensor that detects a minute flow rate of a fluid. As shown in FIG. 1, each thin film semiconductor sensor 18 is configured such that a thin film sensor portion (thin film portion) 4 having a bridge shape is provided on a concave portion 3 formed on a silicon substrate (semiconductor substrate) 2. There is. A thin film heater (sensor circuit element) 5 for heating the measurement fluid is provided in the center of the thin film sensor unit 4, and a thin film temperature sensitive resistor for detecting the temperature of the heated fluid to be measured is provided on both sides of the heater 5. The bodies (sensor circuit elements) 6 and 7 are provided. The recess 3 allows the lower surface side of the bridge-shaped thin film sensor unit 4 to face the silicon substrate 2 through the space 9. The space 5 allows the heater 5
And the thin film sensor section 4 on which the temperature sensitive resistors 6 and 7 are formed.
The thermal insulation from the silicon substrate 2 can be achieved. A plurality of such thin film semiconductor sensors 18 are collectively formed as shown in FIG. 2 on a silicon substrate wafer (semiconductor substrate wafer) 19 as the silicon substrate 2 by a micromachining process described later. Here, the individual thin film semiconductor sensors 18 ... Are formed in a rectangular shape in a plan view on the silicon substrate wafer 19, and the boundary portion of each thin film semiconductor sensor 18, which becomes the cut portion 10, is in the thickness direction of the silicon substrate wafer 19. It is divided by the opening groove 17 formed by anisotropic etching. The coordinate system shown in FIG. 1 indicates the crystal orientation of the silicon substrate.

Next, a method for collectively manufacturing a plurality of thin film semiconductor sensors 18 of the present embodiment having the above-mentioned structure on a silicon substrate wafer 19, and the thin film semiconductor sensor 18 concerned.
A method of manufacturing each thin film semiconductor sensor chip 1 from the silicon substrate wafer 19 in which a plurality of are manufactured will be described with reference to the sectional views of FIGS. 3 to 5. 3 to 5
Shows a cross section taken along the line AA in FIG.

First, a silicon substrate wafer 19 having front and back crystal planes of (100), that is, a silicon substrate 2 having a size capable of manufacturing a plurality of thin film semiconductor sensors 18 is prepared (FIG. 3A). Then, on the front and back surfaces of the silicon substrate wafer 19, that is, both surfaces (upper and lower surfaces in the figure) in the thickness direction of the silicon substrate 2 shown in FIG. A predetermined thickness (for example, about 100 to 400 nm in this embodiment) is formed by a sputtering method, a plasma CVD method, or the like (FIG. 3).
(B)). Next, a metal film is vapor-deposited at a predetermined position on one insulating film 12 to have a predetermined thickness (for example, 100 in this embodiment).
(About 400 nm), and the metal film is processed into a desired pattern by photolithography to form a thin film heater 5.
And the temperature sensitive resistors 6 and 7 are formed (FIG. 3C). Here, Ni, Ni—Fe, Pt, or the like is used for the metal film, and a vacuum deposition method, a sputtering method, or the like is applied to the film formation.

Then, a thin insulating film 14 made of, for example, silicon nitride is formed into a predetermined thickness (for example, about 100 to 400 nm in this embodiment) by a sputtering method or the like.
The heater 5 and the temperature sensitive resistors 6 and 7 are formed thereon so as to cover them (FIG. 4D). Next, in order to form the thin film sensor unit 4, as shown in FIG.
Part of 4 is removed by photolithography, and silicon substrate 2
The surface of is exposed and the opening 16 is formed. Insulation film 1
Etching of Nos. 2 and 14 is performed by an isotropic etching solution (buffered hydrofluoric acid or the like (silicon is not etched)) when wet, and by dry etching when dry. Insulation film 1
The openings 16 of 2 and 14 are for forming the thin film sensor section 4 by utilizing anisotropic etching of silicon as described later. In addition, an opening groove 17 is formed in the insulating film 12 or 14 at the position where the cutting portion 10 is formed, and when the thin film semiconductor sensor chip 1 is divided into individual thin film semiconductor sensor chips 1, the opening groove 17 is used as a guide and the cutting portion is cut by a dicing machine. 10 will be formed (described later).

Then, the insulating film 1 is immersed in an anisotropic etching solution which does not attack the insulating films 12, 13 and 14.
Silicon substrate 2 through opening 16 from which 2 and 14 are removed
Are etched to form the concave portion 3, that is, the space portion 9 (FIG. 4 (f)). Here, when the insulating films 12, 13, and 14 are made of silicon nitride, potassium hydroxide (KOH) is used as an anisotropic etching solution for silicon that does not attack the insulating films.
A solution can be used. With potassium hydroxide solution,
The etching rate ratio between silicon crystal planes (100) and (111) is 400: 1 (particularly (111) plane is not shown). Therefore, when a (100) silicon substrate is used, as shown in FIG. 1, the insulating films 12 and 14 are removed in a shape of a non-zero angle with respect to the <011> direction to expose the surface of the silicon (100). Then, the undercut proceeds, and the cross-linked thin film sensor unit 4 including the insulating films 12 and 14, the heater 5 and the temperature sensitive resistors 6 and 7 is formed. In addition,
Since the undercut is fastest in the direction of 45 degrees with respect to the <011> direction, as shown in FIG.
The direction of was set at 45 degrees with respect to the <011> direction. Through the above steps, the thin film sensor section 4 and the space section 9
A semiconductor substrate wafer 19 in which a large number of thin film semiconductor sensors 18 made of, for example, are integrally formed is created.

Next, the space portions 9 of all the thin film semiconductor sensors 18 ... Of the semiconductor substrate wafer 19 are filled with the reinforcing material 20 (FIG. 5 (g)). Here, in this embodiment, the space 20 is filled with the reinforcement 20, and the whole thin-film semiconductor sensor 18 is further covered with the reinforcement 20, whereby each thin-film sensor unit 4 is covered with the reinforcement 20. Thus, all the parts other than the thin film sensor part 4 are integrated with each other to expand the reinforcing surface. The reinforcement 20 is made of a material that can be removed by melting or chemical reaction, or a material that can be removed by heating and vaporizing. Specifically, by dropping a photoresist on the surface of the semiconductor substrate wafer 19 and rotating the semiconductor substrate wafer 19 by a spin coater, all the space portions 9 are filled with the photoresist, and dried to dry the photoresist. Remove the solvent. As a result, the reinforcement 20 made of photoresist is solidified so that the space 20 is completely filled with the reinforcement 20, and the thin-film sensor section 4 facing the space 9 is integrated with the reinforcement 20. Will be. After that, after the adhesive tape 22 is attached to the back surface of the silicon substrate 2, the semiconductor substrate wafer 19 is cut along the opening groove 17 by the dicing device in units of the thin film semiconductor sensor 18 so as not to cut the adhesive tape 22. Then, the cut portion 10 is formed to obtain the individual thin film semiconductor sensor chip 1 (FIG. 5 (h)). In this case, the adhesive tape 2
2 prevents each thin film semiconductor sensor chip 1 from being dissipated.

Then, the reinforcement 20 filling the space 9 and also covering the surface of the thin film sensor 4 is removed by a method suitable for the nature of the reinforcement 20 (FIG. 5).
(I)). Here, in this embodiment, since the reinforcement 20 is made of photoresist, the thin film semiconductor sensor chip 1 connected by the adhesive tape 22 is immersed in a solvent such as acetone or a resist stripping solution to remove the reinforcement 20. It will be. When another reinforcement 20 is used, a removal solution that does not dissolve the thin films or a removal solution having a significantly slower dissolution rate than the dissolution rate of the reinforcement 20 is used when removing the reinforcement 20. .

Although individual thin film semiconductor sensor chips 1 can be obtained by the above-described manufacturing method,
According to this manufacturing method, after filling the space portion 9 provided for each thin film semiconductor sensor 18 with the reinforcement 20,
The semiconductor substrate wafer 19 filled with is cut into individual thin film semiconductor sensor chips 1 by a dicing device,
Since the reinforcement 20 is removed after the cutting, the space 20 is filled with the reinforcement 20 at the time of cutting by the dicing device. Therefore, the thin-film sensor unit 4 facing the space 9 is integrated with the reinforcement 20, and the thin-film sensor unit 4 is reinforced by the reinforcement 20. Therefore, shock (mechanical vibration, cutting of the dicing device) is generated during cutting. Even if there is an impact of water for cooling the blade)
It is possible to prevent the occurrence of breakage.

In the above embodiments, the photoresist was used as an example of the reinforcing material, but the reinforcing material is not limited to this. For example, wax that dissolves in a solvent such as trichlene can be used. If it is solid,
It can be used if the viscosity decreases with increasing temperature. Further, as the thin film semiconductor sensor chip, as long as it has a thin film sensor portion having the above-described shape, it is of course possible to apply it to various thin film semiconductor sensor chips such as a pressure sensor and a gas sensor other than the flow rate sensor.

[0016]

As described above, according to the present invention, when a semiconductor substrate wafer on which a plurality of thin film semiconductor sensors each having a cross-linked thin film portion are collectively cut and divided into individual thin film semiconductor sensor chips. For example, after filling the thin film portion provided for each thin film semiconductor sensor with a reinforcing material in the cross-linking space, the semiconductor substrate wafer filled with the reinforcing material is cut into individual thin film semiconductor sensor chips by a dicing device. After cutting, the reinforcement is removed. Therefore, at the time of cutting by the dicing device, since the reinforcing material is filled in the space portion forming the cross-linked thin film portion, the cross-linked thin film portion is integrated with the portion other than the thin film portion through the reinforcement object, Even if there is a shock (mechanical vibration from the dicing device, a shock of water for cooling the cutting edge of the dicing device, etc.) at the time of cutting, it is possible to prevent the bridging thin film portion from being damaged. Further, since the thickness of the cross-linked thin film portion, that is, the thin film portion on the space portion can be reduced, the sensor circuit element is provided.
The thermal insulation between the thin film part on the space part and the thin film part on the non-space part is also improved, and the detection performance can be improved.

[Brief description of drawings]

FIG. 1 is a plan view of a thin film semiconductor sensor according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a semiconductor substrate wafer in which a plurality of thin film semiconductor sensors according to an embodiment of the present invention are collectively formed.

FIG. 3 is a first cross-sectional view for sequentially explaining a process of manufacturing the thin film semiconductor sensor on the semiconductor substrate wafer in the manufacturing process of the thin film semiconductor sensor chip of the present embodiment.

FIG. 4 is a second cross-sectional view for sequentially explaining a process of manufacturing a thin film semiconductor sensor on a semiconductor substrate wafer in a manufacturing process of the thin film semiconductor sensor chip of this embodiment.

FIG. 5 is a cross-sectional view for sequentially explaining a process of forming a thin film semiconductor sensor formed on a semiconductor substrate wafer into chips in the manufacturing process of the thin film semiconductor sensor chip of the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 thin film semiconductor sensor chip 2 silicon substrate (semiconductor substrate) 4 thin film sensor part (thin film part) 5 heater (sensor circuit element) 6,7 temperature sensitive resistor (sensor circuit element) 9 space part 18 thin film semiconductor sensor 19 semiconductor substrate wafer 20 Reinforcement

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hiroyasu Yuasa 1-2-5 Tomioka Higashi, Kanazawa-ku, Yokohama, Kanagawa Prefecture (72) Inventor Seishiro Oya 2-2-9-304, Kugenuma Ishigami, Fujisawa-shi, Kanagawa (72) ) Inventor Yozo Hirata 1-6-3 Fujimi, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Tokiko Corporation

Claims (1)

[Claims] 1. A thin film portion formed on a semiconductor substrate is provided with a sensor circuit element, and a thin film portion of the portion where the sensor circuit element is provided is formed into a bridge with the semiconductor substrate for thermal insulation. As described above, a plurality of thin film semiconductor sensors each having a space formed between the thin film portion and the semiconductor substrate therebelow are collectively formed on one semiconductor substrate wafer, and the plurality of thin film semiconductor sensors are A method of manufacturing a thin film semiconductor sensor chip, wherein a single semiconductor substrate wafer formed at a time is cut by a dicing device and divided into individual thin film semiconductor sensor chips, wherein a plurality of thin film semiconductors formed on the single semiconductor substrate wafer at a time When dividing the sensor into individual thin film semiconductor sensor chips, the space of each thin film semiconductor sensor provided for each thin film semiconductor sensor The first step of filling the reinforcement, the second step of cutting the semiconductor substrate wafer filled with the reinforcement into individual thin film semiconductor sensor chips by a dicing device, and after cutting, A third step of removing the reinforcement from the space, and a method of manufacturing a thin film semiconductor sensor chip, comprising: