JPS60230048A - Field effect type semiconductor sensor - Google Patents

Abstract

PURPOSE:To facilitate work by forming a high-density doping area closely to the surface of a semiconductor substrate and also adhering a conductive film to the internal surface and opening peripheral edge of a hole formed at the reverse surface side by etching, and thus forming a conductor path. CONSTITUTION:When electrodes of a source 2 and a drain 3 are led out to the reverse surface side of the semiconductor substrate 1 to form conductor paths of conductors 10 and 10, high-density doping areas 5 and 6 are formed of thin layers closely to the surface of the semiconductor substrate 1. On the other hand, holes 8 and 8 reaching them from the reverse surface side are formed by etching and a conductive film 9 is adhered to internal surfaces and opening peripheral edges of the holes 8 and 8. Consequently, the high-density doping areas 5 and 6 are allowed even with the thin layers, so the formation is attained by a general thermal diffusing method and the work is facilitated.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to chemically sensitive field-effect semiconductor sensors used in ion concentration measuring instruments, etc.

[Prior art]

A chemically sensitive field effect transducer is known from Japanese Unexamined Patent Publication No. 139289/1989, etc.
Unlike ordinary field effect transistors that are commonly used for this purpose, they are made of metal (metal)! It has no poles. That is, a reference electrode is immersed in a thin layer of the chemically sensitive surface of the transducer and brought into contact with an aqueous solution containing the substance to be tested, and this thin layer is exposed to the specific substance in the aqueous solution. The structure differs significantly from that requiring a gate electrode because the electric field generated between the source and drain of the semiconductor material is modulated in accordance with the chemical properties of the material. . Such chemically sensitive field effect transducers are often used with the surface layer in direct contact with the bath liquid so that there is no conductive bond between the conductive aqueous solution and the transducer. There must be. However, today in common planar technology all the leads are placed on one surface of the semiconductor device, so
Because there was a chemically sensitive layer on the surface,
Insulation problems arise. Therefore, one solution to this problem is to connect the lead wires to the back side of the semiconductor element.

It has been proposed to take out the material from the surface opposite to the front surface on which the chemically sensitive layer is provided, and an example thereof is disclosed in JP-A-54-30896. As is clear from the above-mentioned publication, this known technology has a structure in which a highly doped region that is largely coupled to the source and drain and forms a conductor path penetrates from the front surface of the semiconductor substrate to the back surface, and a lead wire is formed on the back surface. It is now connected. The formation of this highly doped region from the front surface to the back surface is performed using heat transfer of aluminum. In this way, although the highly doped region is formed by heat transfer of aluminum, the semiconductor substrate made of silicon is quite thick with a thickness of several hundred microns, so it cannot be done using the general thermal diffusion method. This is because it is not possible to form a conductive region that penetrates the semiconductor substrate, and it can only be processed by thermal movement of aluminum, which is not only complicated and inconvenient, but also increases costs and is inconvenient from a practical point of view. . In particular, when the semiconductor substrate is a silicon plate, the heat transfer of aluminum is limited to n-8i, so there is no disadvantage that only P-channel field effect transducers can be created.
1. I don't get it.

[Problems to be solved by the invention]

As mentioned above, since there was a problem that it was not possible to create a tfn channel type sensor with this type of conventional field effect semi-semiconductor sensor, the limitations of the present invention were eliminated and the P channel ffl l u channel type sensor was not created. 9) can be easily produced, and the lead wires can be easily and reliably taken out from the back side using a normal heat diffusion method without relying on a special method called a heat transfer method. By making it possible to mass-produce high-efficiency vehicles using ordinary semiconductor element manufacturing technology, it is possible to provide a low-cost, highly stable semiconductor sensor, and to promote its widespread use. exists. (Means for Solving the Problems) Therefore, in the present invention, a chemically sensitive thin layer is spread to a certain depth away from the surface of the inner layer of a semiconductor substrate such as a silicon plate formed on the surface. A source and a drain arranged symmetrically to form a channel that is wide and partitioned from the surrounding layers, and two heavily doped regions arranged as conductive paths to be largely coupled to the source and drain. In a field-effect semiconductor sensor: 1. A thin layer is provided in the two high concentration doping regions near the surface of the semiconductor substrate, and holes are formed by etching that reach the respective high concentration doping color regions from the back surface of the semiconductor substrate. A conductive film is provided in close contact with the inner surface of the hole and the periphery of the opening, forming the bottom of the tank, and a chemically sensitive thin layer is provided in a highly doped region serving as a conductor path. Several 1O from one surface to a semiconductor substrate that has not been
It is sufficient to form the layer to a depth of about microns, and therefore a desired highly doped region can be obtained by a simple method of thermal diffusion. In addition, for electrical connection between the highly doped region and a conductor such as a lead wire placed on the back side of the semiconductor substrate,
This is also done by making use of holes that are formed by etching to reach the high concentration doping region from the back surface of the semiconductor substrate, and by adhering the conductive film to the inner surface of the holes using methods such as vapor deposition or thermal diffusion. In addition, it is a common method used in semiconductor device manufacturing and is a suitable and easy means for mass production.
Processing is possible regardless of i. In this way, the uninvented sensor can be manufactured using normal methods, which simplifies the process.
Both n-channel and p-channel semiconductor sensors can be fabricated and hereby serve the intended purpose satisfactorily.

【Example】

Embodiments of the present invention will be described below based on the drawings. Figure 1 is a longitudinal cross-sectional view of a field-effect semiconductor sensor, and Figure 2 is a cross-sectional view taken along line A-A' in Figure 2. Figure 2 is a plan view with the chemically sensitive thin layer and insulating protective layer removed. It is. A source (
2) The source (2) and drain (3) are arranged so as to face each other and form a thin flat channel +41 between them.
) and the channel (4) are manufactured by conventional methods in semiconductor technology. Roughly on the surface side of the semiconductor substrate (1), a heavily doped region f5+ coupled to the source (21) and a heavily doped region f5+ coupled to the drain (3) are formed.
6) are formed by diffusion bonding. In order to electrically stabilize the semiconductor structure, a cha~
The channel limiter circle is formed by diffusion bonding. Thereafter, a stabilizing layer is formed on the surface of the semiconductor substrate [11], followed by a chemically sensitive thin layer (
7), this thin layer (7) being suitably a thin film of, for example, PH-sensitive glass. When the surface processing of the semiconductor substrate fi+ is completed in this way, the holes f81. +8] is drilled. This hole +81.181 is filled with the heavily doped region +51. The hole is drilled until it reaches +61, and after the hole is finished, a conductive film, such as a metal film (9) such as aluminum, is coated on the inner surface of the hole (8) using a process such as vapor deposition.

[Bottom surface and side circumferential surface] and the opening periphery are formed in close contact with each other. Then, in this conductive Mt91, there is f''1 on the back surface.
．． ), place a conductor such as a lead wire (1
0) are joined by heat and pressure. The thus manufactured semiconductor sensor is bonded and integrated with an insulating frame 021 covered with an insulating glass 04 to obtain a field effect semiconductor sensor. The use of the above-mentioned semiconductor sensor to measure chemical properties such as ion concentration and reducing gas concentration was disclosed in Japanese Patent Laid-Open No. 51
This is as disclosed in, for example, Japanese Patent Publication No. -1392139. (Effects of the Invention) The present invention includes a conductor path for taking out the source (2) electrode and the drain [3]'IE electrode to the back side of the semiconductor substrate +11.
A heavily doped region 151 is formed as a thin layer near the surface of the semiconductor substrate +11. [61, and a hole +81. etched so as to reach both the doped regions +5L and [6+] from the back surface side. Since the conductive film (9) is closely attached to the circumferential surface of the conductive film (9), the highly doped regions 151 and 161 can be easily processed because they can be formed using a relatively shallow layer and can be formed by a general thermal diffusion method. In addition, since the holes f8+ and +81 can be formed by etching, this is also a common processing method in semiconductor device manufacturing technology and is simple, making it possible to mass-produce low-cost sensors. The present invention is particularly advantageous because it can be manufactured by a general heat diffusion method, so that the conventional one using heat transfer of aluminum can be easily manufactured.
Whereas it was possible to manufacture only channel ones, P
Channel, n-channel, and n-channel semiconductor sensors can also be manufactured, and this type of field effect semiconductor sensor has an excellent effect of expanding the range of use.

[Brief explanation of drawings]

1 and 2 are a longitudinal sectional view and a partially omitted plan view according to an embodiment of the present invention. il+... Semiconductor substrate, (21... Source. (3)... Drain, (4)... Channel. +51 +6 High concentration doping region, (7)...
Thin layer. (8)...hole, (9j...conductive film, [+01...
conductor.

Claims (1)

[Claims] 1. A chemically sensitive thin layer (71) is formed on the inner layer of a semiconductor substrate such as a silicon plate (11), which is spread away from the surface to a certain depth, and is in contact with surrounding layers. A source (2) and a drain (3) arranged symmetrically to form a channel (4) partitioned into Highly doped region 151.
161, wherein the two heavily doped regions [1i1. [61 is a semiconductor base [(11,000, which is provided in a thin layer near the surface of 11,
Semiconductor substrate (11f) backside holes +84 and +8 reaching each of the high concentration doping regions (5) and (6) from the back surface 1
+ is provided by etching, and the holes +81.
A conductive film +97 is closely attached to the inner surface and the periphery of the opening of the conductive film (9), and the conductive film (9) is doped with a high concentration of 1511+.
61 and placed on the back side of the semiconductor substrate Ron! conductor ll0
1.001 A field-effect semiconductor sensor, characterized in that it forms a conductor path for connecting with 1.001.