JP2016152271A - Method for manufacturing vertical hall element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a vertical hall element with stable and high sensitivity while minimizing manufacturing cost.SOLUTION: A method for manufacturing a vertical hall element includes a process for forming a semiconductor region, which includes a step of injecting impurities over a plurality of times, into a region where the semiconductor region is to be formed and a thermal diffusion step of diffusing the impurities having been injected over the plurality of times. A semiconductor region of a magnetic detection part is thermally diffused after impurities are injected in a depth direction over a plurality of times, so that the concentration change in the depth direction is minimized, a concentration is maintained at a constant level, and the detection sensitivity of a vertical hall element is stabilized.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for manufacturing a vertical Hall element that uses a Hall effect to detect a magnetic field component horizontal to a semiconductor chip surface.

  The magnetic detection principle of the Hall element will be described. When a magnetic field perpendicular to the current flowing in the material is applied, an electric field (Hall voltage) is generated in a direction perpendicular to both the current and the magnetic field. Obtaining the strength of the magnetic field from the magnitude of the Hall voltage is the principle of magnetic detection by the Hall element.

In the case of a vertical Hall element that detects a magnetic field component that is horizontal to the semiconductor chip surface, a current needs to flow perpendicularly to the chip surface. Therefore, since a depth is required for the diffusion layer of the magnetic detection unit, an epitaxial substrate is often used for forming a vertical Hall element.
As a vertical Hall element on a silicon substrate, there is a vertical Hall element having a concentration change in a diffusion layer of a magnetic detection unit. (For example, see Patent Document 1)

JP 2005-333103 A

When the diffusion layer of the magnetic detection unit has an impurity concentration gradient, the concentration gradient varies depending on an error due to manufacturing, and the Hall element sensitivity also changes accordingly. Therefore, it is difficult to create a highly sensitive Hall element. Although there is a method using an epitaxial substrate for stabilization of sensitivity in manufacturing, an IC manufacturing process using a Hall element increases, resulting in an increase in manufacturing cost.
Therefore, an object of the present invention is to provide a high-sensitivity Hall element having a stable sensitivity while suppressing manufacturing cost in a vertical Hall element.

In order to solve the above problems, the present invention uses the following means.
That is, a semiconductor region having a predetermined conductivity type is formed in a semiconductor substrate, and a current supply pair and a voltage output pair are provided on the surface of the semiconductor region, and a current including a component perpendicular to the surface of the substrate is A vertical Hall element that outputs a Hall voltage signal corresponding to the magnetic field component when a magnetic field component parallel to the surface of the substrate is applied to the magnetic detection unit while being supplied to the magnetic detection unit in the semiconductor region In the manufacturing method, the semiconductor region includes a step of implanting a plurality of impurities having different depths and a thermal diffusion step, and the step of implanting the plurality of impurities has a first implantation depth and a first dose. And a second impurity implantation step in which impurities are implanted at a second implantation depth that is deeper than the first implantation depth and at a second dose amount that is less than the first dose amount. Characterize Using the manufacturing method of the type Hall element.

  By using the above means, a change in the concentration of the diffusion layer in the depth direction is suppressed, so that stable Hall element sensitivity can be obtained. In addition, since the manufacturing process can be reduced as compared with the case of using an epitaxial substrate, the manufacturing cost can be reduced.

The top view and side view of a vertical Hall element are shown. It is a figure which shows concentration distribution of the magnetic detection part which performed impurity implantation twice by this invention. It is a figure which shows the impurity concentration distribution of the magnetic detection part of the conventional Hall element.

Examples of the vertical Hall element according to the present invention will be described.
FIG. 1 illustrates a schematic structure of a vertical Hall element. FIG. 1A is a plan view schematically showing the planar structure of the Hall element, FIG. 1B is a longitudinal sectional view taken along the cutting plane AA of FIG. c) shows a cross-sectional view in the transverse direction along the cut plane BB in FIG.

  The Hall element includes a semiconductor layer 1 made of, for example, P-type silicon, and an N-type semiconductor region 3 formed as a diffusion layer by introducing, for example, an N-type conductive impurity on the substrate surface. Has been. Further, a diffusion layer 2 made of, for example, P type is formed in the semiconductor layer 3 so as to isolate the element from other elements. In the region surrounded by the diffusion layer 2 on the surface of the semiconductor region 3, contact regions 4a to 4e in which the impurity concentration (N-type) is selectively increased are formed. The N-type semiconductor region 3 is sometimes called an N-well.

  These contact regions 4a to 4e are electrically connected to terminals S, G1, G2, D1, and D2, respectively, through electrodes (wirings) disposed there. In this Hall element, the contact regions 4a and 4c are paired with the contact region 4b to form a current supply pair. On the other hand, the contact regions 4d and 4e are formed at each end of the voltage output pair. It is equivalent.

  When a constant drive current is passed from the terminal S to the terminal G1 and from the terminal S to the terminal G2, the current flows from the contact region 4a formed on the substrate surface through the diffusion layer 3 and below the diffusion layers 2a and 2b. , Flow into contact regions 4b and 4c, respectively. In this case, a current containing a component perpendicular to the substrate surface flows through the diffusion layer 3. For this reason, when a magnetic field including a component parallel to the substrate surface is applied to the diffusion layer 3, the Hall voltage corresponding to the magnetic field between the terminals D1 and D2 arranged in the direction perpendicular to the current by the Hall effect described above. Vh is generated and a magnetic field can be detected.

In the vertical Hall element of this embodiment, since a current containing a component perpendicular to the substrate surface flows, the diffusion layer 3 needs to be deep with respect to the substrate. In this case, it is desirable that the concentration distribution of the diffusion layer 3 is constant, but once the impurity is introduced by the ion implantation method, the concentration varies depending on the distance from the surface and does not become constant. Therefore, as shown in FIG. 2, when the diffusion layer 3 is formed, impurities are introduced twice or more, and then thermal diffusion is performed so that the impurity concentration of the diffusion layer 3 is constant over a wide range. For example, phosphorus is implanted at a dose of 4.0 × 10 ¹³ / cm ² at an energy of 60 keV, and further phosphorus is implanted at an energy of 150 keV at a dose of 1.1 × 10 ¹⁴ / cm ² , and thermal diffusion (900 ° C. , 30 minutes), the concentration gradient in the depth direction is reduced.

FIG. 2 shows a concentration profile in the depth direction of the N-well due to N-type impurities. Curve 6 is a concentration profile after thermal diffusion of phosphorus implanted at an energy of 60 keV and a dose of 4.0 × 10 ¹³ / cm ² / cm ² , and curve 5 is a dose of 1.1 × 10 5 at an energy of 150 keV and phosphorus. It is the density | concentration profile after thermal diffusion of what was inject | poured by ¹⁴ / cm < ² >. Then, by thermal diffusion, the concentration profile of Nwell combined with each other can be made to be a substantially constant profile up to a predetermined depth as shown by a curve 7. In particular, between the peak position when phosphorus is injected for the first time and the peak position when phosphorus is injected for the second time, or a little wider, the peak position and phosphorus when phosphorus is injected for the first time is 2 The concentration can be made almost constant between the positions exceeding the peak at the time of the second injection. Thereby, the current component flowing in the direction perpendicular to the substrate surface can be stabilized, and the sensitivity as the Hall element can be stabilized. For comparison, FIG. 3 shows an impurity concentration distribution diagram of a magnetic detection part of a conventional Hall element. Since the impurity implantation is performed once, the impurity concentration profile is not constant, and has an upwardly convex profile having a maximum value.

  In the above, the first impurity implantation is carried out at a prescribed depth of the substrate 1 with a prescribed dose, and then the second impurity implantation is made deeper than the first impurity implantation so as to reduce the dose. Although the example of the two impurity implantations having the above conditions is shown, the impurity implantation may be performed three or more times. If the ion implantation species are the same, when the acceleration voltage is increased, it is possible to obtain a concentration profile with less concentration variation by reducing the dose.

1 Substrate (P-sub)
2 Element isolation (P type)
3 Diffusion layer (N type)
4a to 4e Contact region (N +)
5 Concentration profile by second impurity implantation 6 Concentration profile by first impurity implantation 7 Concentration profile by first and second impurity implantation 8 N concentration profiles G1, G2, S, D1, D2 by impurity implantation in the prior art Terminal

Claims (3)

A current flows vertically in a depth direction viewed from the surface of the semiconductor substrate in a semiconductor region in which an N-type impurity is diffused provided in the semiconductor substrate, and between the terminals provided in a direction perpendicular to the current A vertical Hall element manufacturing method for detecting a component of a magnetic field parallel to the surface of the semiconductor substrate by a voltage generated in
Implanting impurities into the region where the semiconductor region is to be formed a plurality of times;
A thermal diffusion step of diffusing the impurities implanted multiple times;
Forming the semiconductor region comprising:
The step of injecting impurities over a plurality of times,
A first impurity implantation step of implanting a first impurity with a first implantation depth and a first dose;
A second impurity implantation step of implanting a second impurity with a second implantation depth deeper than the first implantation depth and a second dose amount smaller than the first dose amount;
The manufacturing method of the vertical Hall element characterized by including. After the thermal diffusion step,
The impurity concentration in the depth direction is constant between the position of the first impurity peak in the first impurity implantation step and the position of the second impurity peak in the second impurity implantation step. The method for producing a vertical Hall element according to claim 1.   2. The method of manufacturing a vertical Hall element according to claim 1, wherein the step of injecting the impurity a plurality of times is a step of injecting the impurity twice.