JPS60210243A - Semiconductor composite sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical field The present invention relates to a semiconductor composite sensor that can simultaneously measure the concentration of one chemical substance and the pressure. This field relates to a semiconductor composite sensor that uses electric field effect and piezoresistive effect for pressure measurement.

(2) Background technology Conventionally, gate insulated field effect
A semiconductor sensor has been proposed that utilizes the structure of a FET (FET) to measure the concentration of ion-active chemical substances in an electrolyte. These are IonSensitiveFi
eldEffectTransistor(ISFE'
l'l or Chemical FET (CHEMF
It is called ETl, and there are descriptions about it in Japanese Patent Publication No. 54-24317, etc.

FIG. 1 is a basic configuration diagram of a cross section including a gate portion of a CIIEMFET. This is a structure in which the gate metal of the MISFET is removed and the gate 1/insulating layer is brought into direct contact with the atmosphere to be measured.

On the other hand, when a certain amount of stress is applied to a semiconductor,
Various configurations of silicon diaphragm type semiconductor pressure sensors have also been proposed, which utilize the curved nature of the piezoresistive field to change its resistance field.

A typical example is shown in FIG. This is to prevent the adverse effects of moisture, alkali metal ions, etc. contained in the atmosphere to be measured on the semiconductor sensor when the sensor is used to measure the pressure of an atmosphere such as a liquid.

These sensors both use silicon substrates, so
By making full use of recent advanced silicon IC manufacturing technology, miniaturization and integration of compensation circuits are possible, and various new applications have been proposed. For example, in medical applications, a sensor may be attached to the tip of a catheter and inserted into a blood vessel to directly and continuously measure information inside the body. That is, C
Measurement of ion concentration in blood using a HEMFET, acetylcholine, urea, penicillin, etc. using biofunctional interest as an I'S ratio, and measurement of intravascular or intracardiac blood pressure using a pressure sensor. Continuous in-body measurements using these CHEMFET and pressure sensors individually are also very effective, but from a clinical medical point of view, it is extremely important to monitor blood pressure at the same time as measuring ion concentrations and other substance concentrations. It becomes data.

Although this is possible by simultaneously installing a CHEMFET and a semiconductor pressure sensor in one catheter,
Mounting each individual sensor in the same catheter requires very complicated manual work, and such implementation is almost impossible in real life.

As a solution to overcome these problems, the patent application 1983-
Semiconductor composite sensors have been proposed such as 23833U. As shown in the cross-sectional view of the structure in Figure 3, these are devices in which a layer selectively sensitive only to a specific substance to be measured is provided on the gate part of an insulated gate field effect transistor on the same semiconductor substrate. It has a structure that incorporates two types of sensors into one element: a 14-structure field-effect semiconductor sensor and a semiconductor pressure sensor that uses a diffused resistor formed on a diaphragm as a pressure sensing part.

However, there is a limit to miniaturization simply by combining two kinds of seven snowflakes, and multi-J'i 1.
It is impossible to realize a catheter tip type sensor that can simultaneously measure the concentration and pressure of chemical substance No. 1.

(3) Aspect 1 of the invention The present invention provides an ultra-small semiconductor composite sensor that can simultaneously measure the concentration and pressure of a polynomial chemical substance and can be attached to the tip of a catheter, etc. There is a particular thing.

(4) Structure of the Invention The semiconductor composite sensor according to the present invention consists of a gate insulated field effect transistor, which is basically a completely separate element.
・There are two types of semiconductor pressure sensors: a field-effect semiconductor sensor with a structure on which a layer is selectively sensitive only to a specific substance to be measured, and a semiconductor pressure sensor with a structure that uses a diffused resistor formed on a diaphragm as a pressure-sensitive part. Rather than simply incorporating the sensors on the same semiconductor substrate as a single element, the structure of each sensor is organically integrated to achieve true structural complexity.

Specifically, this is achieved by simultaneously using the diaphragm, which is the pressure-receiving part that occupies most of the total element area of the pressure sensor, as the sensitive part of the field-effect semiconductor sensor. In other words, the diaphragm part of a pressure sensor normally only has a diffused resistance formed thereon and is used mechanically, but as a semiconductor element, it is completely unusable due to the change in characteristics caused by the deflection of the diaphragm. It is considered unavailable. Although the diaphragm is an essential component of this pressure sensor, it is difficult to use for increasing sensor sensitivity and multiplexing. Similarly, the diaphragm is not used as a semiconductor element, but as a contact part with the atmosphere to be measured, and only the surface area of the element is small. By using the necessary field effect semiconductor as the chemical sensing part of the laser, the element surface of the composite sensor can be efficiently utilized and the overall element can be miniaturized.

In fact, when such a semiconductor composite sensor is used for one time, it is sufficient to incorporate one semiconductor pressure sensor, and even if multiple semiconductor pressure sensors are incorporated, it is expected that the accuracy will improve slightly by averaging the output values of each sensor. However, the field-effect type '-1'-conductor sensor is very effective because it can measure many items simultaneously by incorporating a large number of sensors forming various types of sensitivity.

Possible types of this sensitive film are listed together with the measurement target shown in brackets: 3N4゜AI 2
03, 'I'a305 (H-'- ion), various NAS (NagO-A1g03-5 i02 synthetic 1 glass (K+ ion Na+ ion) Valino Mine fixation 1
1% (K'-ion, fixed with various crown ethers) y
;t, [: K++ ions, Ag+ ions, TI+ ions, etc.:] urease-immobilized membrane [urea], lipase-immobilized IN [neutral side W), benicillinase-immobilized 11% C-penicillin], anti-albumin antibody-immobilized membrane [albumin],
Acetylcholinesterase fixed membrane [acetylcholine]
There is a door.

Furthermore, when forming multiple types of sensitizers at the same time, it is conceivable to form a hydrophobic organic polymer film that is not sensitive to any chemical substance for use as a reference electrode. Such polymer membranes include polyethylene,
Possible materials include polypropylene and polyvinyl chloride.

(5) Examples of the invention In the following, the present invention will be explained based on the drawings of the embodiments.

FIG. 4 is a diagram showing the structure of a semiconductor composite sensor as an embodiment of the present invention. This figure shows a case where 4 field-effect sensors and 7 diaphragm-type pressure sensors are formed into the same element. FIG.

In the figure, the size of the sensor is 1.0mm x 3.0
mm, the thickness is assumed to be 0.15 mm, and the thickness of the diaphragm part is assumed to be 20 μm.

In order to realize a composite sensor with this structure, a patent application
8-51145, it is essential to have a multilayer structure including a conductive layer such as a metal between the gate acid layer and the chemically sensitive layer of a field effect sensor.
Using this conductive layer, the positions of the gate part t1-1 and the chemically sensitive part must be connected. That is, in the case of this embodiment, there are 4 game 1 part structures (35, 36,
37 and 381 are formed on a silicon single crystal substrate (32), and are guided by conductive layers (39i, 0, 4, 1, 4, 2) included in the multilayer TFA structure of each gate part. (4 types of 16 science sensitive layers (4, 8, 1, 45, 4, 6) on or around 331
1 is formed and -C exists.

Therefore, in the left half of Fig. 49(a), there are 4 diffused piezoresistors (34) as pressure sensitive parts in the diaphragm part (33) and its surrounding area, and 4. +, q reaction part (4, 3, 4, 1, 4, 5, 401) is formed in a concentrated manner, resulting in a 4'l structure. At this time, it is important to note that the four parts forming the bridge diffusion resistance (34
) is such that the mechanical stress applied to it is transmitted exactly equally, or at least with regular symmetry. For example, the diaphragm part has a total thickness of about 211 μm, and most of it is a single crystal silicon substrate (32), but the upper part has a 5i0 thickness of about 1 μm.
22 Which insulating layer (49), conductive layer such as polysilicon made conductive by implanting AI or impurity ions +
39.4・U, 4・1, 4□2) Four types of chemically sensitive layers (
43, 44, 45, 4, 6) and an insulating layer (50) serving as a protective layer, conductive layers (39, 4, (1, 4,1,4
21 should be formed on the diaphragm part (33) at a geometrically symmetrical position with respect to the diffused piezoresistor (34), and the insulating layer ω), which is a protective layer, should also be formed under unnatural stress. It needs to be flattened so that it does not.

The conductive layers (39, 40, 41, 421 have a thickness I Ii
Since the thickness of the diaphragm is approximately 1.5 m, it is not thought that if the particle is made of AI or polysilicon, it will have a large effect on the way the diaphragm bends.

In addition, as a protective layer, Si 3N4, AI 203, SiOxN, which can be formed at low temperature by plasma CVD, can be used.
y, Al0xNyPSG (Phospho-3
il 1cate P20b 5iO21,PbO-A
I20a・5iO2(Lead -Al umino-
5i l 1cate l , PbOB2O3-3i
02 (Lead-Boro-5ilicate l,
PbO・A120a・B20; 5iO2(Lead
-Alumino-Boro-5ilicate
A single layer structure of 1 or polyimide resin, or a multilayer structure of a combination of these materials can be considered. Furthermore, the arrangement of the chemically sensitive layers (43, 44, 45, 4(i)) must be determined in consideration of their thickness and mechanical strength.

On the other hand, the right half of Fig. 4(b) shows the signals taken out from the gate part of the field effect sensor [35, 30, 37, 38+ and 4 field effect sensors and the bridge of the diffused piezoresistor]. A signal processing circuit section (4'711) to be processed is further formed with a contact metal layer (48) for connecting lead wires for input/output to this circuit.

The contents of the signal processing include (1) temperature compensation and sensitivity compensation of the potential difference detected by the diffusion piezoresistive bridge and its conversion to a pressure value, (11) time-dependent change correction of the field effect sensor and conversion to each measured value. Conversion, 011) Judgment of whether each measurement item is normal or abnormal can be considered.

(6) Effects of the Invention The greatest effect of the invention is that it has become easier to combine and multiplex silicon diaphragm pressure sensors and field effect semiconductor sensors. It is especially effective when combining one pressure sensor and multiple field effect semiconductor sensors.
It becomes possible to incorporate a field effect sensor without increasing the size of the element compared to a pressure sensor alone.

In catheter tip type sensors for medical applications, which is the most promising application example of the semiconductor composite sensor of the present invention, the fact that multiplexing is possible while maintaining the advantage of miniaturization, which is a major feature of semiconductor sensors, is as follows. Although conventional technology is said to have great clinical significance because it can be easily installed in a catheter, it is the first time that it has been possible to simultaneously measure pressure and the concentration of various chemical substances at the same site in the body, which was possible with two hands. The clinical medical significance of this is immeasurable.

A secondary effect of the present invention is that the sensitive part for pressure and various i+1 chemical substances can be formed centrally around the diaphragm part, so that it can be mounted on a catheter etc. in the same way as a single-function sensor. It will be easy to some extent.

In other words, it's in the blood, which is very bad? In order to use a semiconductor sensor in a single body, the sensitive part must be in direct contact with the blood, and the lead wires must be completely insulated and separated from the blood. In reality, epoxy resin, silicone resin, etc. are used as adhesives and insulators for mounting, so if there are river spots at the locations where the sensitive parts are assembled, the current resin coating technology will not be able to deal with this, so the sensitive parts will be placed in one place. It is desirable to concentrate on

[Brief explanation of the drawing]

Figure 1 is a diagram showing the basic configuration of a cross section including the gate part of a field-effect semiconductor sensor using a conventional silicon single crystal substrate, and Figure 2 is a diagram showing a semiconductor pressure sensor with improved atmospheric resistance according to the conventional technology. Fig. 3 is a diagram showing the first side of the basic sensor (111 structure). Fig. 3 is a cross-sectional view of a semiconductor composite sensor in which a field effect sensor and a diaphragm pressure sensor are formed in the same element according to the prior art. Fig. 4 is a diagram showing the structure of a semiconductor composite sensor in which 41 field-effect sensors and one diaphragm-type pressure sensor are formed in the same element, which is an embodiment of the present invention. in,
(a) is a plan view thereof, and (1)) is a sectional view centered on the field effect sensor section. ] Silicon single crystal substrate (p-type) 2 Source diffusion region (n-type) 3 Drain diffusion region (n+ type) 4 Channel section 5 Insulating layer (1.3iO21) 6 Insulating layer (2.5iaN4) 7 Chemical sensitivity Layer 8 Metal WJ for lead contact (Al19 Silicon single crystal substrate (n-type) 10 Diaphragm part 11 Diffused piezoresistance (p-type) 12 Lead part in expansion 11 (p'l-type) ■3 Silicon epixaxial growth N (n-type 114 p-type diffusion region 15 insulating layer (ex 5i3N41) 16 metal layer for lead contact (All 17 silicon single crystal substrate (p-type) 18 diaphragm part 19 diffused piezoresistance (n-type) 20 diffusion lead Part (n green type) 21 Silicon epitaxial growth layer (p″″ type) 22
Source diffusion region (n-(type)) 23 Drain diffusion region (n-type) 24 Channel section 25 Diffusion region for substrate contact (p-type) 2fin
Ten-shaped diffusion region 27 Insulating layer (Sil1 28 Chemical sensitive layer 29 Metal layer for diffused resistance lead contact (Al130)
Metal layer for source/substrate common lead contact (A1)
31 F rain/lead contact metal layer (Al13
2 Silicon single crystal substrate 33 Diaphragm part 34 Diffused piezoresistor (4 pieces) 35 Field effect sensor gate 1 part (part 1) 36 η
(Part 2) 37 (Part 3) 38 (Part 4) 39 Conductive material layer (Part 1) 4 (1ft (Part 2) 4.1 // (Part 3) 4・2 (Part 4) 4・3 Chemically sensitive layer (Part 1) 44 Chemically sensitive layer (Part 2) 45 (Part 3) 46 '/ (Part 4) 47 Signal processing circuit section 48 Metal layer for lead contact (A1) 4.9 Insulating layer ( ex 5iO21 50 protective insulating layer (ex Si3N4) Agent Patent attorney - Representative ■ Tsukasa L:, Near, '1 Official 1 Figure 2 Figure W4 Figure (G) (b)

Claims (1)

[Claims] (]) A field-effect semiconductor sensor and a diaphragm in which a layer selectively sensitive only to a 4-r constant measured substance is provided in the gate portion of a gate-insulated field-effect l-range disk. A semiconductor pressure sensor using the diffused resistor formed on the semiconductor substrate as a pressure sensing part. A semiconductor composite sensor comprising one or more sensitive layers of a field effect semiconductor sensor formed therein. (2) The semiconductor composite sensor according to claim 1, wherein the soil conductor substrate is a single crystal silicon substrate.