DE10244096B4 - Spinning current Hall sensor with homogeneous space charge zone - Google Patents

Abstract

A spinning current current sensor having a plurality of current measuring contacts (1-4) for applying an operating current (I) and picking up a Hall voltage, comprising a current-conducting layer (110) in which the operating current (I) flows, and a contiguous layer (120, 410, 420) between which, upon operation of the spinning current current sensor (100), there is created a space charge zone (130) which limits the current flow in the current conducting layer (110) to a current carrying region, the adjacent layer (120, 410, 420) a plurality of contacts (221, 223, 421-424), to which a voltage is applied, which is dimensioned such that the operating current (I) when fed in a first direction and in the opposite direction by the the same current-carrying region flows, characterized in that means for generating a near the surface (340) of the current-conducting layer (110) lying barrier layer (330, 630) are provided.

Description

The invention relates to a spinning current Hall sensor according to the preamble of patent claim 1.

In the current measurement with conventional Hall tiles arise in addition to the Hall voltage additional unwanted voltage components (offsets) which distort the measurement signal. These offsets are caused in particular by geometry errors, piezoresistive effects, inhomogeneous temperatures, etc. in the sensor.

To improve the measurement accuracy, it is known to use spinning current Hall sensors, with which the offsets can be eliminated substantially from the measurement signal. A typical example of a spinning current Hall sensor is in 1 shown.

1 shows a plan view of a known spinning current Hall sensor with multiple contacts 1 - 4 at which an operating current I ₁₃ or I ₂₄ in the direction shown, as well as in the opposite direction can be applied. At the respective orthogonally arranged contact pair while the Hall voltage is tapped. The spinning current Hall sensor 100 is operated in rotation, ie the operating current is switched in the direction of arrow A to the next contact pair. For example, a current I ₁₃ is first impressed and a voltage U ₂₄ measured and then successively the currents and voltages I ₂₄ , U ₁₃ ; I ₃₁ , U ₄₂ ; and I ₄₂ , U ₃₁ imprinted or measured. By averaging all voltage contributions U over a period, the offset can ideally be eliminated. The current can optionally also rotate continuously and the voltage can be measured continuously.

At the in 1 However, realized realization occur on other parasitic effects that can not be eliminated by applying the spinning current principle. These are explained below on the basis of 2a and 2 B explained in more detail.

2a shows a section along the line II, II in 1 , The illustrated current sensor 100 consists of an n-type layer 110 on a p-type layer 120 is applied. The n-type layer 110 is also via the n-contact diffusions 101 . 103 electrically to the contacts 1 . 3 connected. The p-layer 120 is via a back contact 121 connected to a reference potential. When a voltage U _{13 is applied} , a current I _{13 flows} through the current-conducting layer 110 from contact 1 to contact 3 ,

In operation of the sensor 100 is the pn junction 120 . 110 Sperrgepolt and it turns a space charge zone 130 a, as indicated in dashed lines, the current flow in the current-conducting layer 110 limited to a live area. Because of the higher voltage drop between the contact 1 and the back contact 121 is the space charge zone 130 near the contact 1 thicker than near the contact 3 ,

If the operating current I _{31 is applied} in the opposite direction, as in 2 B is shown, so is the space charge zone 130 because of the higher potential at the contact 3 near the contact 3 thicker than near the contact 1 ,

The operating current I thus flows through depending on the feed contact 1 . 3 different current-carrying regions in the current-conducting layer 110 , This leads to the aforementioned offset components that can not be eliminated by the spinning current operation.

From the post-published font DE 102 40 404 A1 a Hall sensor is known in which a residual leakage voltage, which arises due to the variation of the width of a space charge zone between Hall plate and the surrounding semiconductor substrate, can be reduced. This is accomplished by forming the Hall plate in a line type region in the substrate with a zone of another conductivity type adjacent thereto. Both zones are provided with contacts in order to be able to apply both a control current and a compensation current. By means of the compensation current, the thickness of the space charge zone lying between the zones is influenced.

It is the object of the present invention to further improve the measurement accuracy of a spinning current Hall sensor.

This object is achieved according to the invention by the features specified in claim 1. Further embodiments of the invention are the subject of dependent claims.

The essential idea of the invention is to provide a known spinning current current sensor, comprising a current-conducting layer in which an operating current flows, and an adjacent layer, not only with one but with a plurality of contacts on the adjacent layer, at which a voltage is applied, which is dimensioned such that the operating current when fed in a first direction and in the opposite direction through the substantially same area of the current-carrying layer flows. The current-carrying region thus remains unchanged in both current directions. Offset components, which in the prior art due to a current flow through different areas have emerged, can thus be eliminated.

A preferred way to create a non-changing current carrying region is to set the space charge zone at the pn junction between the adjacent layer and the current-carrying layer substantially uniformly thick in the direction of current flow. The operating current therefore flows in both directions through a current carrying region having a substantially uniform effective cross section.

According to a preferred embodiment of the invention, the same number of contacts of the adjacent layer as current or measuring contacts are provided. This results in a particularly simple realization of the Hall sensor.

According to a first embodiment, the contacts of the adjacent layer are arranged on the rear side of the Hall sensor and are located opposite the current or measuring contacts of the sensor arranged on the upper side with respect to a center plane of the sensor.

The voltage drop across a contact pair of the contacts of the adjacent layer is preferably equal to the voltage drop across a contact pair of the current or measuring contacts.

According to another embodiment of the invention, the current-conducting layer is embedded in an adjacent layer which surrounds the current-conducting layer laterally and below (in the case of an n-conducting layer this is a p-conducting layer and vice versa). In this embodiment, the contacts of the adjacent layer are arranged on the same side as the current or measuring contacts and are preferably also on the surface of the sensor.

The spinning current Hall sensor may further comprise means for creating a barrier layer at or near the surface of the electrically conductive layer. As a result of this barrier layer, the semiconductor surface, as a significant contributor to the noise, is excluded from the flow of current and noise is thus reduced. The current flows in this case only in a lower-lying zone.

To produce the barrier layer, either a shielding diffusion with an opposite conductivity as the current-conducting layer can be introduced into the latter or z. B. an electrode on the surface of the current-conducting layer (with intervening insulation) are applied, by means of which an inversion layer is generated by applying a voltage.

The electrode or the shielding diffusion is preferably also contacted with a plurality of contacts.

Radially adjacent contacts of the electrically conductive layer, the adjacent layer and the surface shield are preferably on the same radial line with respect to a central axis of the sensor.

The contacts on the surface of the sensor are preferably evenly spaced circumferentially.

The spinning current-Hall sensor according to the invention preferably also comprises an evaluation logic and / or an amplifier circuit, which are also integrated on the sensor chip.

The invention will now be described by way of example with reference to the accompanying figures. Show it:

1 a plan view of a spinning current Hall sensor according to the prior art;

2a , b is a sectional view of the spinning current Hall sensor of 1 at different current directions;

3 a sectional view of a spinning current Hall sensor according to an embodiment of the invention;

4 a sectional view of a spinning current Hall sensor with a shielding diffusion;

5a a sectional view of a spinning current Hall sensor with a buried p-layer;

5b a plan view of the Spinning Current Hall sensor of 5a ;

6a a sectional view of a spinning current Hall sensor with a shield electrode; and

6b a plan view of the Spinning Current Hall sensor of 6a ,

Regarding the explanation of 1 . 2a . 2 B Reference is made to the introduction to the description.

3 shows the same cross section of a spinning current Hall sensor 100 like in the 2a . 2 B , The Hall sensor 100 consists of an n-type layer 110 on a p-type layer 120 is applied and the over n-contact diffusions 101 . 103 electrically to the contacts 1 - 4 connected. The line property (p or n) of the individual layers 110 . 120 can also be the other way around.

Unlike the 2a . 2 B is the layer 120 not just a single contact 121 but over a total of four contacts (of which only the two contacts 221 . 223 are shown) connected. In operation of the Hall sensor 100 At the rear contacts, a voltage is applied, which is dimensioned such that the space charge zone 130 at the locked-pole pn junction ( 110 . 120 ) in the current direction substantially has a homogeneous thickness. In a current flow in the opposite direction ( 3 - 1 ), a voltage is applied at which the space charge zone 130 not or not significantly changes. The overlying current-carrying region of the current-conducting layer 110 thus remains unchanged in both directions. Consequently, no additional offset components due to different current-carrying regions can occur.

The contacts are the current or measuring contacts 1 - 4 with respect to a median plane of the sensor 100 arranged opposite. The voltage drop between two contacts 221 . 223 is in particular the same size as the voltage drop between two power contacts 1 . 3 , This leaves the thickness of the space charge zone 130 substantially constant in the lateral direction, and the region through which the current flows remains unchanged in both current directions.

In the embodiment of 3 becomes both the current-conducting layer 110 as well as the adjacent layer 120 activated in spinning current mode (rotating). The evaluation of the Hall voltages is carried out in the usual way to the current-conducting layer 110 ,

In principle, the current-conducting layer 110 have any even number of contacts. The adjacent layer 120 in this case has an equal number of contacts.

4 shows a cross section through a spinning current Hall sensor compared to that of 3 additionally a shielding diffusion layer 310 having. The semiconductor surface 340 is a significant noise contributing area. Due to the additional p-type shielding diffusion layer 310 becomes an area near the semiconductor surface 340 exempt from the flow of electricity. The current I ₁₃ thus flows only in the interior of the current-conducting layer 110 ,

The shield diffusion layer 310 is in contact 301 - 304 connected (of which in 4 only the contacts 301 . 303 are shown). At the contacts 301 - 304 becomes a voltage in the reverse direction of the pn junction 310 . 110 connected, which is a barrier 330 (Space charge zone) at the pn junction 310 . 110 generated. The to the contacts 301 - 304 applied voltage is dimensioned such that the current-carrying region does not change or does not change significantly in current flow in a first direction and in the opposite direction.

Lateral adjacent contacts 1 . 301 . 303 . 3 are arranged in alignment. The shield diffusion layer 310 as well as the current-conducting layer 110 and the adjacent layer 120 are operated in spinning current mode, ie rotating.

5a shows a realization of a spinning current Hall sensor 100 which is integrated into a chip. Instead of the shift 120 , with back contact, as in 4 is shown, in this embodiment, a buried p-layer consisting of a buried p-layer 420 and a p-diffusion 410 , used.

The buried layer 420 is again in a layer 440 embedded, the back of a contact 121 connected.

The layer 410 . 420 surrounds the current-conducting layer 110 completely and is about front-side contacts 421 - 423 , (of which in 5a only the contacts 421 . 423 are shown) connected. Lateral adjacent contacts 421 . 1 . 301 ; 303 . 3 . 423 are again arranged in alignment. For isolation reasons, the p-type diffusion regions 410 in the lateral direction of an adjacent n-type layer 210 surround.

Between the areas 410 and 210 thus arises with appropriate polarity a barrier layer 430 that serves the isolation.

The n-type layer 210 preferably comprises an evaluation logic and / or an amplifier circuit (not shown), which are thus integrated on the sensor chip.

5b shows a plan view of the Hall sensor 100 from 5a in which the spatial arrangement of the contacts 421 - 424 ; 1 - 4 ; 301 - 304 , as well as the individual layers 210 . 410 and 110 is shown. As you can see, the contacts are 421 - 424 ; 1 - 4 ; 301 - 304 arranged rotationally symmetrically about a common center, wherein the contacts are equally spaced in the circumferential direction. Lateral adjacent contacts 421 - 424 ; 1 - 4 ; 301 - 304 are further arranged in alignment on a radial line.

The in 5a shown spinning current Hall sensor 100 has the disadvantage that a misalignment of the Abschirmdiffusionsschicht 310 opposite the contact diffusions 101 . 103 the current-conducting layer 110 generates additional offset contributions. Because of the manufacturing technology, in which the shielding diffusion layer 310 and the contact diffusions 101 . 103 are each created with separate mask levels, the probability of misalignment is great. This disadvantage can be caused by a on the current-conducting layer 110 applied electrode 610 , in the contact holes for the contacts 1 - 4 be etched in, be solved.

6a shows such an embodiment of a spinning current Hall sensor, in which instead of the Abschirmdiffusionsschicht 310 an electrode 610 is provided with a barrier layer (inversion layer) 630 can be generated. The electrode 610 covers the entire surface 340 the current-conducting layer 110 ,

Between the electrode 610 and the current-conducting layer 110 is an insulation layer, for. As an oxide layer, arranged (not shown). The electrode 610 may for example consist of a polysilicon layer.

The electrode 610 is with multiple contacts 601 - 604 at which a voltage is applied, which generates a barrier layer in a near-surface region. The operating current I ₁₃ can thus only in a lower-lying area of the electrically conductive layer 110 flow and get between the contact diffusions 101 . 103 not to the sensor surface 340 ,

For shielding the noisy semiconductor surface 340 it is beneficial to use the electrode 610 very close to the areas 410 to submit to.

The use of polysilicon as the material for the electrode 610 is particularly advantageous, since in this case windows can be produced by means of ion implantation, the contact diffusion 101 - 104 can be made virtually self-adjusting. A misalignment of the shielding means ( 610 ) to the contact diffusions 101 - 104 and the associated additional offset can thus be prevented.

6b shows again a view of the Hall sensor of 6a in which the rotationally symmetrical arrangement of the contacts 421 - 424 ; 1 - 4 ; 601 - 604 can be seen. The actuation of the contacts takes place in an analogous manner to the previously described embodiments of the spinning current Hall sensor in the spinning current mode. This results in a comparable lateral voltage drop across the electrode 610 generated as over the current-conducting layer 110 , so that the current-carrying region in the current-conducting layer 110 when the current is fed in a first direction (eg I ₁₃ ) and in the opposite direction (eg I ₃₁ ) remains substantially constant.

LIST OF REFERENCE NUMBERS

1-4

contacts

100

Spinning current Hall sensor

101-104

contact diffusions

110

electrically conductive layer

120

adjacent layer

121

reference contact

130

Space charge region

210

n-type layer

221-224

back contacts

301-304

Contacts of the shielding diffusion

310

Abschirmdiffusionsschicht

330

Space charge region

410

p-type region

430

Space charge region

420

buried layer

440

outer semiconductor layer

601-604

electrode contacts

610

electrode

I

operating current

Claims (11)

Spinning current current sensor with multiple current or measuring contacts ( 1 - 4 ) for applying an operating current (I) and picking up a Hall voltage, comprising an electrically conductive layer ( 110 ), in which the operating current (I) flows, and an adjacent layer ( 120 . 410 . 420 ) between which during operation of the spinning current current sensor ( 100 ) a space charge zone ( 130 ), which causes the current flow in the current-conducting layer ( 110 ) is confined to a live area, the adjacent layer ( 120 . 410 . 420 ) several contacts ( 221 . 223 ; 421 - 424 ), to which a voltage is applied, which is dimensioned such that the operating current (I) flows through the same current-carrying region when fed in a first direction and in the opposite direction, characterized in that means for producing a near surface ( 340 ) of the electrically conductive layer ( 110 ) barrier layer ( 330 . 630 ) are provided. Spinning current current sensor according to claim 1, characterized in that at least as many contacts ( 221 . 223 ; 421 - 424 ) of the adjacent layer ( 120 . 410 . 420 ) such as current or measuring contacts ( 1 - 4 ) are provided. Spinning current current sensor according to claim 1 or 2, characterized in that the current or measuring contacts ( 1 - 4 ) and the contacts ( 221 . 223 ) of the adjacent layer ( 120 ) with respect to a median plane. Spinning current current sensor according to claim 1, characterized in that the current-conducting layer ( 110 ) into an adjacent layer ( 410 . 420 embedded), which the electrically conductive layer ( 110 ) completely surrounds laterally and below. Spinning current current sensor according to claim 4, characterized in that the adjacent layer ( 410 . 420 ) Contacts ( 421 - 424 ) located on the same side of the spinning current current sensor ( 100 ) are arranged as the current or measuring contacts ( 1 - 4 ). Spinning current current sensor according to claim 1, characterized in that the means for producing the barrier layer ( 330 . 630 ) a shield diffusion layer ( 310 ), which enter into the electrically conductive layer ( 110 ) is introduced. Spinning current current sensor according to claim 1, characterized in that the means for producing the barrier layer ( 330 . 630 ) one on the surface ( 340 ) of the electrically conductive layer ( 110 ) applied electrode ( 610 ). Spinning current current sensor according to one of the preceding claims, characterized in that the adjacent layer ( 410 . 420 ) in a further outer semiconductor layer ( 210 . 440 ) is embedded. Spinning current current sensor according to claim 4, characterized in that the contacts ( 1 - 4 ) of the electrically conductive layer ( 110 ), The contacts ( 221 . 223 ; 421 - 424 ) of the adjacent layer ( 120 . 410 . 420 ), as well as contacts ( 301 - 304 . 601 - 604 ) the means for producing a near-surface barrier layer with respect to a central axis of the sensor ( 100 ) are arranged radially in alignment. Spinning current current sensor according to one of claims 1 or 5 to 9, characterized in that the contacts ( 1 - 4 ) of the electrically conductive layer ( 120 . 410 ) and / or the contacts ( 221 . 223 ; 421 - 424 ) of the adjacent layer ( 120 . 410 . 420 ) and / or contacts ( 301 - 304 ; 601 - 604 ) the means for producing the near-surface barrier layer ( 330 . 630 ) on the surface ( 340 ) of the sensor ( 100 ) are equally spaced circumferentially. Spinning current current sensor according to one of the preceding claims, characterized in that an evaluation logic and / or an amplifier circuit on the sensor ( 100 ) is integrated.

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