JPH0228385A - Magnetism detector - Google Patents

Abstract

PURPOSE:To prevent the film quality from deteriorating even if it goes through the heat treatment process after MR element formation by providing a ferromagnetic magnetoresistance element of a film on the region that the impurity of a silicon dioxide film is below the specified concentration. CONSTITUTION:This is constituted of a substrate 1, a silicon dioxide film 5 which is a film formed on the main face of the substrate 1 and containing impurity and has a region that the impurity is below the specified concentration at least at one part of it, and a ferromagnetic magnetoresistance(MR) element 10 being a film which is formed on the region that the impurity of the silicon dioxide film 5 is below the specified concentration and contains Ni for its main ingredient. Since the MR element 10 is formed on the region that the impurity of the silicon dioxide film 5 is below the specified concentration this way, the deterioration of the film quality of the MR element 10 can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic detection device in which a thin film ferromagnetic magnetoresistive element (hereinafter referred to as an "rMR element") is formed on a substrate as a magnetic detection means.

[Conventional technology]

As a means of detecting magnetism, M is mainly composed of ferromagnetic material.
A magnetic detection device in which a thin film of an R element is formed on a substrate has been proposed.

Such a magnetic detection device is configured to take advantage of the fact that the resistance value of the MR element changes when it receives magnetism (magnetic field), and outputs the change in magnetism as, for example, a voltage change.

Since the output signal of the above-mentioned magnetic detection device is very small, the signal from the MR element Lot is amplified by an IC100 such as an amplifier circuit or a waveform shaping circuit, and then output as shown in Figure 2. are doing. In addition, 10 in Figure 2
2 is a lead, and 103 is a molded case. Recently, there has been an increasing demand for integrating MR elements and their ICs.

FIG. 3 is a sectional view showing a conventional structure of a magnetic detection device in which such an MR element and an IC are integrally formed. The manufacturing process of this magnetic detection device will be explained using FIG. 5. First, a P-type Si wafer 1 is used (step 200), and its surface is thermally oxidized (step 201) to open a predetermined region. An N° type buried layer 2 is formed by diffusing Sb (antimony) or As (arsenic) from the opened region (step 202). Step 20
After removing the thermal oxide film formed in step 1, epitaxial growth is performed to form N-type epitaxial N3 with a low impurity concentration.
(Step 203) After thermally oxidizing the surface of the epitaxial layer 3 (Step 204), the portion that will become the isolation region is opened to form the isolation region 4 in which B (boron) is diffused (Step 205). .

Then, after selectively forming an insulating film made of Sing, B is diffused to form a P' type scattering layer 6 which becomes a base region (step 207), and P is similarly diffused to form an emitter region and a collector (step 207). An N'-diffusion layer 7 is formed as a contact region with the epitaxial layer 3) (step 20).
8). A contact portion is formed by selectively opening the insulating film (step 209). In addition, insulation RF! i5 shows what is in this state. After that, Al is vapor-deposited and the wiring 9
Step 210), heat treatment is performed, and contact is made (Step 211). After that, Fe, C.

An MR element 10 made of a thin film of a ferromagnetic material containing Ni as its main component, that is, a Ni/Co film or a Ni/Fe film, is deposited by about 200 to 2,000 people using a vacuum evaporation method, and then photoetched to form a predetermined shape. A pattern is formed (step 2I2). Furthermore, after forming a protective film 11 to protect the bipolar IC and MR element formed as described above (step 213), the protective film 11 at the electrode terminal portion is removed and an opening 12 is formed. Form an electrode terminal.

Finally, heat treatment is performed to recover the transistor characteristics that have changed due to the formation of the MR element IO2 protective film 11, improve the film quality of the MR element 1o, etc. (step 215).

In the above manufacturing process, N+diffusion N of bipolar IC
7 (step 208) is usually POC
This is done by gas phase diffusion using l3 gas, but at this time,
P, which is a diffusion source, also diffuses into the insulating film 5, and a PSG film 8 is formed on the surface thereof. This PSG film 8 has functions such as gettering, so it is left as it is in normal ICs, but when the MR element 10 is formed on this PSG film 8 in the above-mentioned magnetic detection device, the glass No bipolar IC on the substrate or Si wafer
It has been found that the film quality, such as electromagnetic properties, is significantly inferior to that of an MR element deposited on a 5iOz film formed simply by thermally oxidizing the surface without forming a 5iOz film.

[Problem to be solved by the invention]

In view of the above facts, the inventors of the present application have further conducted experimental considerations and found that the MR element 10 in the portion near the insulating film 5 of the IC
It was found that the membrane quality of the throat had deteriorated. It was found that this deterioration was caused by the reaction of P as an impurity contained in the PSG film 8 on the surface of the insulating film 5 of the IC with the MR elements 1 and 0 during the heat treatment (Step 2I5). Ta.

The present invention has been made based on this point, and is an MR device whose film quality does not deteriorate even after the heat treatment process after forming the MR element.
An object of the present invention is to provide a magnetic detection device in which an element is formed on a substrate.

[Means to solve the problem]

In order to achieve the above object, the magnetic detection device of the present invention includes a substrate, a film formed on the main surface of the substrate and containing impurities, and at least a part of which has a region where the impurity is below a predetermined concentration. a silicon dioxide film having N
The present invention is characterized by comprising: a thin film ferromagnetic magnetoresistive element containing i as a main component;

Alternatively, the impurity may be P, and the predetermined concentration may be 5 Pros mol%.

〔Example〕

Hereinafter, the present invention will be explained using embodiments shown in the drawings.

FIG. 1 is a cross-sectional view showing the configuration of this embodiment, in which the pipe 91C section A, which processes the signal from the MR element 10, and the MR
An element portion B and an electrode terminal portion C are shown. The manufacturing process of this magnetic detection device is basically the same as the manufacturing process of the magnetic detection device that the inventors of the present application prototyped and experimented with before the present invention, as explained using FIG.
□) In the upper layer of the insulating film 5, there is a bipolar IC0
The diffusion source P at the time of forming the N1 diffusion layer 7 is diffused,
A PSG film 8 containing a high concentration of P as an impurity is formed.

According to this embodiment, in the manufacturing flow shown in FIG. 5, after the step 208 of forming the N+ diffusion layer 7, the step of removing the PSG film 8 shown in step 300 is performed.

In this step 300, an opening 13 is formed by partially removing the PSG film 8 in the area where the MR element 10 is planned to be formed in the MR element part B, and whether or not the lower layer P is contained at a low concentration is determined. The insulating film 5 not included is exposed. Specifically, a mixed solution of ammonium fluoride, hydrofluoric acid, and water is used as an etching solution, and a portion containing P at a relatively high concentration,
Using the difference in etching speed with other parts, P
The PSG film 8 containing a high concentration of is selectively removed.

In this case, by reducing the ratio of hydrofluoric acid in the etching solution, the overall etching rate is reduced and controllability is improved.

After going through steps 209 to 211, a pattern of the MR element 1o is formed in this opening 13.

FIG. 4 shows the relationship between the phosphorus concentration of the PSGl 18 and the rate of change in resistance of the MR element 10 when a Ni/Co film is used as the MR element 1o. Generally, when forming the N/diffusion layer 7, which is the emitter region of a bipolar IC, the phosphorus concentration is 1.
Since the PSG film 8 of 0 to 20 PtoS mol% is formed, the resistance change rate of the MR element 1° is the same as that of N on the impurity-free silicon dioxide film (that is, the phosphorus concentration is 0 PzOs mol%).
This decreases by 20% to 50% compared to the case where an i/Co film is created, but in this example, PS with a high phosphorus concentration was used.
Since the G film 8 is removed and the phosphorus concentration of the insulating film 5 in the region where the MR element 1o is planned to be formed is set to 5 PzOs mol% or less, the reaction between the MR element 10 and P is suppressed, and even after the heat treatment process in step 215, the MR element remains intact. The reduction in the rate of change in resistance of 10 can be reduced to approximately 10% or less, and an MR element with excellent film quality and electromagnetic properties with no practical problems can be obtained. In addition, since the PS film 8 on other IC parts remains as it is, it is possible to expect gettering and other effects on the IC.
Deterioration of characteristics can be prevented.

Next, another embodiment of the present invention will be described. This example is an example in which Ad (arsenic) is used as a diffusion source in the bipolar IC0N9 diffusion layer forming step in the above example.
The manufacturing process of the magnetic detection device in this embodiment is also basically the same as the manufacturing process explained using FIG. 3, and the description of processes that can be the same will be omitted. In this example, since A, which is considered a dangerous substance in a gas state, is used,
The step of forming the N diffusion N7 of Stella 7' 208 is performed by ion implantation. After this step 208, the insulating film 5 is formed.
In the next step 300, the insulating film 5 in the area where the MR element is to be formed is etched by about 1000 layers using a hydrofluoric acid etchant. The insulation y5, which contains almost no , is exposed.

Figure 6 shows the insulation when using a Ni/Co film as the MR element 10.
It shows the relationship with the resistance change rate of the R element 1o. Generally, when forming the N° expanded rP1 layer 7, which is the emitter region of a bipolar IC, a layer of l×10” (
1/c+1) is stored, so that the resistance change rate of the MR element IO is N t on the impurity-free silicon dioxide film.
The concentration on the surface of the insulating film 5 exposed as a result of etching in step 3oo is 1Xl, as shown in the diagram.
If it is controlled to be less than 0'' (1/cj), the decrease in the rate of resistance change can be reduced to less than 10%, making it possible to create an MR element with excellent film quality and electromagnetic properties with no problem in practical use. can do.

In addition, when ion-implanting As into silicon dioxide,
A3 is not introduced deeply into silicon dioxide,
Normally, the acceleration energy during ion implantation is 130K.
When set to eV, about 500 people were injected into the air depth, and
At the limit of the current technological level, the acceleration energy is 160K.
Even if it is eV, the implantation depth is about 700 air at most.

Therefore, if the insulating film 5 is air-etched by about 1000 people as described above, most of A can be removed and the rate of change in resistance will hardly decrease.

Although the present invention has been described above using the above-mentioned embodiments, the present invention is not limited thereto and can be modified in various ways, for example as shown below, without departing from the spirit thereof.

■The impurity contained in the silicon dioxide film may be B, etc. in addition to P9A, so the MR element is a BPSG film containing impurities (B, P) below a predetermined concentration, or BS
It may be formed on a G film. Further, the film used as the MR element may be a Ni/Fe film,
Compared to the Ni/Co film described above, the value of the resistance change rate is smaller, but since the magnetic domain structure is the same, the characteristics tend to be the same.

In this way, any substance can be selected for the impurity contained in the silicon dioxide film and the MR element, and in short, step 21
Any material may be used as long as the impurity is diffused into the MR element during the heat treatment in step 5. This is because it is thought that the rate of change in resistance decreases due to its diffusion.

(2) The IC formed within the substrate may be, for example, a MO3 IC in addition to a bipolar IC.

〔Effect of the invention〕

As described above, according to claim 1 of the present invention, since the MR element is formed on the region of the silicon dioxide film where the impurity concentration is below a predetermined concentration, there is an effect that deterioration of the film quality of the MR element can be suppressed.

Moreover, according to claim 2, there is an effect that the decrease in the rate of change in resistance of the MR element can be made 10% or less.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a magnetic detection device according to Embodiment 1 of the present invention, FIG. 2 is a configuration diagram of a conventional magnetic detection device, and FIG. Fig. 4 is a graph showing the relationship between the phosphorus concentration of the PSG film and the resistance change rate of the MR element, Fig. 5 is a flow chart showing the manufacturing process of the magnetic detecting device, and Fig. 6 is a cross-sectional view of the magnetic detecting device. Arsenic concentration and M
It is a graph showing the relationship with the resistance change rate of the R element. DESCRIPTION OF SYMBOLS 1...Si wafer, 5...Insulating film, 7...Nₛ diffusion layer. 8...PSG film, 10...MR element, 13...opening.

Claims (2)

[Claims] (1) a substrate, a silicon dioxide film formed on the main surface of the substrate and containing impurities and having a region in which the impurity is at a predetermined concentration or less in at least a part thereof; Impurities are formed on a region with a predetermined concentration or less, and N
A magnetic detection device comprising: a thin film ferromagnetic magnetoresistive element containing i as a main component; (2) The magnetic detection device according to claim 1, wherein the impurity is P (phosphorus), and the predetermined concentration is a phosphorus concentration of 5P_2O_5 mol%.