DE10244096A1 - Spinning current Hall sensor with homogeneous space charge zone - Google Patents

Abstract

The invention relates to a spinning current Hall sensor with a plurality of current or measuring contacts (1-4) for applying an operating current (I) and tapping a Hall voltage, a current-conducting layer (110) in which the operating current flows, and an adjacent layer (120, 420), between which, when the spinning current Hall sensor is in operation, a space charge zone (130) is formed which limits the current flow in the current-conducting layer (110) to a current-carrying area. To avoid offset components during the measurement, it is proposed to provide the adjacent layer (120, 410, 420) with a plurality of contacts (221-224; 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 through the substantially same current-carrying area.

Description

The invention relates to a spinning current Hall sensor according to the generic term of claim 1.

When measuring current with conventional Hall plates in addition to the Hall voltage additional undesirable Voltage components (offsets) that falsify the measurement signal. These offsets are particularly affected by geometry errors, piezoresistive effects, causes 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 substantially eliminated 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 , to which an operating current I ₁₃ or I _{24 can be applied} in the direction shown and in the opposite direction. The Hall voltage is picked off at the orthogonally arranged contact pair. 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 pair of contacts. For example, a current I ₁₃ is first impressed and a voltage U _{24 is} measured, and then the currents and voltages I ₂₄ , U ₁₃ ; I ₃₁ , U ₄₂ ; and I ₄₂ , U ₃₁ impressed or measured. The offset can ideally be eliminated by averaging all the voltage contributions U over a period. The current can optionally rotate continuously and the voltage can be measured continuously.

At the in 1 However, the realization shown occurs further interfering effects that cannot be eliminated by using the spinning current principle. These are based on the following 2a and 2 B explained in more detail.

2a shows a section along the line II, II in 1 , The current sensor shown 100 consists of an n-type layer 110 that are on a p-type layer 120 is applied. The n-type layer 110 is also about 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 for contact 3 ,

In operation of the sensor 100 is the pn junction 120 . 110 reverse polarized and there is 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 close to the contact 1 thicker than near the contact 3 ,

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

The operating current I flows through depending on the feed contact 1 . 3 different current-carrying areas in the current-conducting layer 110 , This leads to the above-mentioned offset components, which cannot be eliminated by the spinning current operation.

It is therefore the object of the present invention the measurement accuracy of a spinning current Hall sensor.

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

The main idea of the invention is to include a known spinning current sensor a current-conducting layer in which an operating current flows, and an adjacent layer, not just one but several Equip contacts on the adjacent layer, where one Voltage is applied, which is dimensioned such that the operating current at Infeed in a first direction and in the opposite direction the substantially same area of the current-conducting layer flows. The current carrying The area therefore remains unchanged in both current directions. Offset components, those in the prior art due to current flow through different Areas have arisen thus be eliminated.

A preferred way to create a not changing live Area is the space charge zone at the pn junction between the adjacent layer and the current-conducting layer in the direction of the current flow to be set essentially uniformly thick. The operating current flows therefore in both directions through a live area with an im essentially uniform effective cross section.

According to a preferred embodiment of the Invention are as many contacts in the adjacent layer as Strombzw. Measuring contacts provided. This results in a particularly simple implementation of the Hall sensor.

According to a first embodiment are the contacts of the adjacent layer on the back arranged of the Hall sensor and are arranged on the top Current or measuring contacts of the sensor regarding opposite a central plane of the sensor.

The voltage drop across a pair of contacts of the contacts of the adjacent layer is preferred as large as the voltage drop across a pair of contacts of the current or measuring contacts.

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

The spinning current Hall sensor can means for forming a barrier layer at or near the surface of the current-conducting layer. Through this barrier layer the semiconductor surface as an authoritative area contributing to noise excluded from current flow and noise thus reduced. The power is on in this case only in a lower zone.

Can be used to create the barrier layer either shield diffusion with opposite conductivity like the current-conducting layer introduced into the latter or e.g. an electrode on the surface the current-conducting layer (with insulation in between) applied by means of an inversion layer by applying a voltage is produced.

The electrode or the shield diffusion is preferably also contacted with several contacts.

Radially adjacent contacts of the current-carrying 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 Sensors are preferably evenly spaced in the circumferential direction.

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

The invention is illustrated below the attached Figures closer by way of example explained. Show it:

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

2a . b 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 screening diffusion;

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

5b a top view of the spinning current Hall sensor from 5a ;

6a a sectional view of a spinning current hook sensor with a shielding electrode; and

6b a top view of the spinning current Hall sensor from 6a ,

Regarding the explanation of the 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 as in the 2a . 2 B , The Hall sensor 100 consists of an n-type layer 110 on a sliding layer 120 is applied and the n-contact diffusions 101 . 103 electrically to the contacts 1-4 connected. The conduction 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 through a single contact 121 , but via a total of four contacts 221 to 224 (of which only the two contacts 221 . 223 are shown) connected. In operation of the Hall sensor 100 will be on the back contacts 221-224 a voltage is applied which is dimensioned such that the space charge zone 130 at the reverse polarized pn junction ( 110 . 120 ) has a substantially homogeneous thickness in the flow direction. If the current flows in the opposite direction ( 3-1 ) a voltage is applied at which the space charge zone 13U does not change or does not change significantly. The current-carrying area of the current-conducting layer lying above 110 therefore remains unchanged in both current directions. As a result, no additional offset components can occur due to different current-carrying areas.

The contacts 221-224 are the current or measuring contacts 1-4 with respect to a central plane of the sensor 100 arranged opposite each other. The voltage drop between two contacts 221 . 223 is in particular the same size as the voltage drop between two current contacts 1 . 3 , This keeps the thickness of the space charge zone 130 essentially constant in the lateral direction and the area through which the current flows is unchanged in both current directions.

In the embodiment of 3 becomes both the current-conducting layer 110 as well as the adjacent layer 120 controlled in spinning current mode (rotating). The Hall voltages are evaluated in the usual way on the current-conducting layer 110 ,

Basically, 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 major contributor to noise. Due to the additional p-type shielding diffusion 310 becomes an area near the semiconductor surface 340 excluded from the flow of electricity. The current I ₁₃ therefore only flows inside the current-conducting layer 110 ,

Shielding diffusion 310 is in contacts 301-304 connected (of which only the contacts 3C1 . 303 are shown). On the contacts 301-304 becomes a voltage in the reverse direction of the pn junction 310 . 110 connected that a junction 330 (Space charge zone) at the pn junction 310 . 110 generated. The contacts 301-304 applied voltage is dimensioned such that the current-carrying area does not change or does not change significantly when current flows in a first direction and in the opposite direction.

In the lateral direction - adjacent contacts 1 . 301 . 303 . 3 are aligned. Shielding diffusion 310 just like the current-conducting layer 110 and the adjacent layer i20 are operated in spinning current mode, that is to say rotating.

5a shows a realization of a spinning current Hall sensor 100 which is integrated in a chip. Instead of ^the shift 120 , with contact on the back 221-224 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 shift 440 embedded the back of a contact 121 connected.

The layer 410 . 420 surrounds the current-conducting layer 110 complete and is through front contacts 421-423 , (of which only the contacts 421 . 423 are shown) connected. Lateral adjacent contacts 421 . 1 . 301 ; 303 . 3 . 423 are in turn aligned. For reasons of isolation, the p diffusion areas are 410 in the lateral direction from an adjacent, n-conducting layer 210 surround.

Between the areas 410 and 210 With appropriate polarity, a barrier layer is created 430 that serves for isolation.

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

5b shows a top view of the Hall sensor 100 of 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 can be seen, the contacts are 421 - 424 ; 1-4 ; 301-304 arranged rotationally symmetrically around a common center, the contacts being evenly spaced in the circumferential direction. Lateral adjacent contacts 421-424 ; 1-4 ; 301-304 are also aligned on a radial line.

The in 5a shown spinning current Hall sensor 100 has the disadvantage that misalignment of the shield diffusion 310 towards contact diffusion 101 . 103 the current-conducting layer 110 generated additional offset contributions. Because of the manufacturing technology where shielding diffusion 310 and the contact diffusions 101 . 103 generated with separate mask planes, the likelihood of misalignment is high. This disadvantage can be caused by an on the current-conducting layer 110 applied electrode 610 , in the contact holes for the contacts 1-4 be etched in, solved.

6a shows such an embodiment of a spinning current Hall sensor, in which instead of the shield diffusion 310 an electrode 610 is provided with which 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 an insulation layer, for example an oxide layer, is arranged (not shown). The electrode 610 can consist, for example, of a polysilicon layer.

The electrode 610 is with multiple contacts 601-604 provided, to which a voltage is applied, which creates a barrier layer in a region near the surface. The operating current I ₁₃ can therefore only in a lower-lying area of the current-conducting layer 110 flow and reach between the diffusion areas 101 . 103 not to the sensor surface 340 ,

To shield the noisy semiconductor surface 340 it is beneficial to use the electrode 610 very close to the areas 410 to come close.

The use of polysilicon as the material for the electrode 610 is particularly advantageous since in this case windows can be created through which the contact diffusions can be achieved by means of ion implantation 101-104 can be produced quasi 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 a top view of the Hall sensor from 5a , in which the rotationally symmetrical arrangement of the contacts 421-424 ; 1-4 ; 601-604 can be seen. The contacts are controlled in an analogous manner to the previously described embodiments of the spinning current Hall sensor in spinning current mode. There is a comparable lateral voltage drop across the electrode 610 generated as over the current-conducting layer 110 so that the current carrying Ge offers in the current-conducting layer 110 when the current is fed in in a first direction (e.g. I ₁₃ ) and in the opposite direction (e.g. I ₃₁ ) remains essentially constant.

1-4

Iontakte

100

Spinning current Hall sensor

101-104

contact diffusions

110

electrically conductive layer

120

adjoining layer

121

reference contact

130

Space charge region

210

n-type layer

221-224

rear contacts

301-304

contacts 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

510

electrode

I

operating current

Claims (12)

Spinning current current sensor with multiple current or measuring contacts ( 1-4 ) for applying an operating current (I) and tapping a Hall voltage, comprising a current-conducting layer ( 110 ) in which the operating current (I) flows and an adjacent layer ( 120 . 410 . 420 ), between which when the spinning current current sensor is operating ( 100 ) a space charge zone ( 130 ) that creates the current flow in the current-conducting layer ( 110 ) limited to a current-carrying area, characterized in that the adjacent layer ( 120 . 410 . 420 ) multiple contacts ( 221-224 ; 421-424 ), to which a voltage is applied which is dimensioned such that the operating current (I) flows through the essentially same current-carrying region when fed in in a first direction and in the opposite direction. Spinning current current sensor according to claim 1, characterized in that at least as many contacts (221-224; 421-424) of the adjacent layer ( 120 . 410 . 420 ) like 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 ( 221-224 ) of the adjacent layer ( 120 ) face each other 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 ) is embedded, which is the current-conducting 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 ), which is on the same side of the spinning current current sensor ( 100 ) are arranged like the current or measuring contacts ( 1-4 ). Spinning current current sensor according to one of the preceding claims, characterized in that means ( 310 . 610 ) to create a near surface ( 340 ) the current-conducting layer ( 110 ) lying barrier layer ( 330 . 630 ) are provided. Spinning current current sensor according to claim 6, characterized in that the means for generating the barrier layer ( 330 . 630 ) a diffusion layer ( 310 ) which are in the current-conducting layer ( 110 ) is introduced. Spinning current current sensor according to claim 6, characterized in that the means for generating the barrier layer ( 330 . 630 ) one on the surface ( 340 ) the current-conducting layer ( 110 ) applied electrode ( 610 ) include. 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 ) the current-conducting layer ( 110 ), The contacts ( 221-224 ; 421-424 ) of the adjacent layer ( 120 . 410 . 420 ), as well as the contacts ( 301 - 304 . 601-604 ) the middle ( 310 . 610 ) to create a barrier layer near the surface with respect to a center axis of the sensor ( 100 ) are radially aligned. Spinning current current sensor according to one of claims 5 to 10, characterized in that the contacts ( 1-4 ) the current-conducting layer ( 120 . 410 ) and / or the contacts ( 221 - 224 ; 921-424 ) four adjacent layers ( 120 . 410 . 420 ) and / or the contacts ( 301-304 ; 601-604 ) the means ( 310 . 610 ) to create the near-surface inversion layer ( 330 . 630 ) on the surface ( 340 ) of the sensor ( 100 ) are evenly spaced in the circumferential direction. Spinning current current sensor according to one of the preceding claims, characterized records that an evaluation logic and / or an amplifier circuit on the sensor ( 100 ) is integrated.