JPH0450648A - Biochemical sensor - Google Patents

Abstract

PURPOSE:To obtain a sensor characterized by stable operation, easy handling and easy machining by using a transparent substrate such as silicon-on-saphire (SOS) substrate in an optical-address-potential response (LAP) sensor. CONSTITUTION:Specular polishing is performed on both surfaces of a transparent saphire substrate S. A P-type silicon film Si is formed on one surface of the SOS substrate S. A high-concentration doped region P is formed on the SOS substrate S other than the light receiving part of the film Si. The surface including the island-shaped light receiving silicon part is covered with an insulating film SiX, and an electrode T is formed. Thus, the LAP sensor is formed. With this constitution using the SOS, the biochemical sensor characterized by stable operation and easy handling and machining is obtained.

Description

[Detailed description of the invention] The present invention relates to the structure of a biochemical sensor.

Photoaddressed potential response sensor (LAP sens)
or-Light-addressable p
otensiometric 5ens.

r) is a device having the structure of electrolyte solution 1/insulating layer 2/silicon semiconductor 113/ as shown in FIG. where RE is a saturated KCL-silver-silver chloride reference electrode and V
-8 is a bias voltage, and 1 is a current system. A light irradiation pulse is applied from the back surface of the silicon semiconductor substrate 3 by a light emitting diode LED, etc., and the light is generated by carriers induced at the interface of the insulating layer 27' and the semiconductor layer 3. Current system I
Measure with.

This photocurrent takes a certain maximum value with respect to the voltage applied between the solution and the silicon semiconductor, and this voltage
'Since it corresponds to the surface potential at the interface of the insulating layer 2, chemical changes in the electrolyte solution can be detected. Conventionally, photo-addressable potential-responsive sensors use a silicon substrate to produce MetaT
A device with a -1n5ulator-Silicon (MIS) structure in which metal is removed is formed and manufactured.

One side of this sensor is covered with an insulating layer 2, but the silicon is exposed on the other side, so it must be electrically insulated from the solution in some way, and the silicon substrate 3 is inherently fragile, so handling of this sensor is difficult. be careful,
I was making it complicated. Another disadvantage is that the energy of the incident light must be increased because light is incident on the back surface of a thick silicon substrate, causing optical loss. Furthermore, the front side is a device and the back side is pre-filled! Since it is an iF1 window, it would be better to be able to process both sides. In this respect, silicon substrates have the disadvantage that it is difficult to align them with the front surface when processing the back surface.

The present invention solves the above-mentioned drawbacks, and provides a biochemical sensor that is electrically insulated from solutions, operates stably, is easy to handle, and is also easy to process, suitable for oral production, and inexpensive. The purpose is to realize the following.

FIG. 2 is an explanatory diagram of the photo-addressable potential responsive sensor of the present invention, in which a silicon-on-sapphire (hereinafter referred to as 5O3) substrate is used. First, a P-type silicon film 3i is formed on one surface of a sapphire substrate S with a double-sided mirror surface l1Ill.
Make the O8 board. Silicon acid: Apply approximately 1 μm of silicon dioxide group Si○2 to the #P surface. Next, the silicon dioxide group other than the light-receiving portion is removed and a high concentration impurity is doped to form a heavily doped region P+.

Next, remove the silicon dioxide group on the island-shaped light-receiving silicon part, and remove all the clean silicon dioxide film silicon pattern.
In a 0 μm x 80 um opening, a high concentration impurity doped portion located away from the light receiving portion is formed under the electrode to the substrate. With the above structure, the insulation 113 of the sapphire substrate S
ix/Silicon 11 surface S1 is brought into contact with the solution, and a light pulse is irradiated from the sapphire substrate surface on the opposite side to insulate II.
/Polarization can be generated at the silicon interface. Furthermore, parts other than the electrode parts to the substrate can be easily electrically insulated from the solution. Further, FIG. 3 shows an example in which a large number of devices are arranged on the same sapphire substrate. The above silicon
An on-sapphire (SO8) substrate is prepared, and about 1 μm of silicon dioxide group is attached to the silicon surface. Next, a large number of 80 μm×8 Q μm silicon dioxide groups in the fIA region arranged at intervals of W are left, and all other silicon dioxide groups are removed. Next, the silicon surface from which the silicon dioxide film has been removed is doped with impurities at a high concentration. Next, the above 8
Silicon dioxide llSi 0 in the area of 0μm×8Qμm
2 and a silicon nitride film 513N4 are formed respectively. Next, a large number of 80 μm arrayed at equal rM intervals
The external electrode T is taken out from a part of the high concentration impurity doped region surrounding the tI4 region of the X8Qμm opening. With the above structure, a large number of minute sensors can be easily fabricated independently on the same substrate using a layer doped with impurities at a high concentration.

FIG. 4 is an example of a photo-addressable potential responsive sensor in which a light entrance window is provided on the back surface of a sapphire substrate. When irradiating light onto the back side of a sapphire substrate, there is a limit to how much light can be focused on a minute area using a lens or optical fiber when using a laser beam or LED as a light source. Irradiation to a minute area can be easily achieved by providing a minute light entrance window on the back surface of the sapphire substrate. In the above-mentioned sensors arranged in large numbers on the same sapphire substrate, reflection #l1RE of copper etc. on the back surface
is applied, and fine windows are opened using the photo process of the semiconductor IC process. In reality, it is possible to create a window of 7 μmφ, and even if a light source such as a laser beam or LED has some spread, it is possible to selectively irradiate a minute area.

FIG. 5 shows another example in which a glass plate G or a quartz plate is used as a transparent substrate that transmits light. A transparent electrode film such as 5OO^indium tin oxide (iTo) is formed on one side of a double-sided amtir-polished glass plate or a quartz plate. On this film, an amorphous semiconductor film such as amorphous silicon yarn is applied.
300 OA shadow formation. Next, the amorphous semiconductor film other than the light receiving portion is removed to expose the transparent electrode. Here, the bridge portion may be in the form of discrete islands or a continuous surface on the transparent bridge film. Next, apply an insulating film such as a clean silicon dioxide group or silicon nitride film.
0004 is formed. Finally, the insulating film away from the light receiving section is removed to expose the transparent electrode film and form electrodes for the sensor. It is clear that in addition to the above, transparent organic materials can be used to create a LAP sensor similar to the above example.

According to the present invention, since a transparent substrate having excellent light transmittance and high insulation properties is used, the stability of the sensor in a solution is improved. In particular, sapphire substrates are resistant to chemicals and have strong mechanical strength, making them easy to handle. In addition, double-sided mirror-finished transparent substrates are not only suitable for sensors that use light, but are also convenient for semiconductor processes such as photo processing on the back side, such as processing light entrance windows. It can be processed at low temperatures, sensors of various shapes can be made, and it is possible to easily realize low-temperature, inexpensive, and highly functional sensors, which is of great practical significance.

[Brief explanation of drawings]

FIG. 1 is a HfF4 diagram of potentiometry using a conventional optically addressed potential responsive sensor, and FIGS. 2, 3, 4 and 5 are structural diagrams of an embodiment of the present invention. In the figure, S is a sapphire substrate, S is silicon, Six is an insulating film, LED is a light emitting element, and ■ is an electrode. Patent applicant Shindengen Kogyo Co., Ltd. Figure 2 Figure 1 Figure 3

Claims (4)

[Claims] (1) In a photo-addressable potential-responsive sensor that detects chemical changes in an electrolyte solution by detecting changes in photo-induced current generated by light irradiation at the electrolyte solution/insulating layer/semiconductor layer interface, a double-sided mirror surface is used. A P-type or N-type semiconductor film is formed on one surface of a transparent substrate such as polished sapphire that transmits light, and an island-shaped semiconductor region surrounded by an inactive region having ohmic properties is formed in this semiconductor film. . A biochemical sensor, characterized in that an insulating film is formed over the entire film, and an electrode lead-out portion is provided in an inert region having ohmic properties and separated from the island-shaped semiconductor region. (2) In the above sensor, a transparent electrode film is formed on one surface of a light-transmitting transparent substrate made of a double-sided mirror surface such as sapphire, glass, or an organic substance, and an amorphous semiconductor film is formed on this film, An insulating film is deposited on these films,
The biochemical sensor according to claim 1, wherein the electrode extraction portion is provided in a part of the transparent electrode film. (3) Place the surface of the semiconductor film on the transparent substrate in contact with the solution, and irradiate pulsed light from the opposite transparent substrate surface to generate carriers at the semiconductor-insulating film interface and cause polarization. A biochemical sensor according to claims (1) and (2). (4) A biochemical sensor according to claims (1), (2), and (3), characterized in that a large number of the sensors are arranged on the same transparent substrate.