TWI477018B - Transient voltage suppressor circuit, and diode device therefor and manufacturing method thereof - Google Patents

Description

Transient voltage suppressor circuit and diode element used therein and manufacturing method thereof

The present invention relates to a transient voltage suppressor (TVS) circuit and a diode element therefor and a method of manufacturing the same, and more particularly to a TVS circuit capable of withstanding a higher forward current and used therein A diode element and a method of manufacturing the same.

FIG. 1A shows a typical transient voltage suppressor (TVS) circuit 1 for coupling with at least one protected circuit 2 to limit the amplitude of the transient voltage from the input/output pad 3 to protect the The protection circuit 2 is protected from being damaged by transient signals (such as static electricity) having a high voltage. In general, the TVS circuit 1 includes a suppression element S1 for clamping the voltage amplitude of the transient signal and absorbing its current. Since the suppressing element S1 needs to consume a high current in a very short time, it has a large-area PN junction and thus has a very high parasitic capacitance; thus, when the protected circuit 2 is normally operated, it is subjected to The effect of this high parasitic capacitance slows down the operation and limits the application range of the component.

A method for improving the operation speed of the protected circuit 2 is slow. As shown in FIG. 1A, at least one diode element D1 having a small parasitic capacitance is inserted between the protected circuit 2 and the suppressing element S1. The diode element D1 and the PN junction in the suppression element S1 are reversely connected to flow current through the diode element D1, and the suppression element S1 absorbs a high current; this method utilizes a low capacitance series high capacitance In order to reduce the capacitance value, the operating speed of the protected circuit 2 is increased. Although this method can improve the problem that the capacitance of the suppression element S1 is too high, the diode element D1 must still be subjected to the transient signal from the input/output pad 3 in the forward direction. The current, therefore, if the lower capacitance value is to be maintained, the transient signal current value that the TVS circuit 1 can withstand decreases, which also limits the application range of the TVS circuit 1.

Figure 3A shows a cross-sectional view of a prior art diode element 100 for use in a TVS circuit; and Figure 3B shows a characteristic of electrostatic withstand voltage and parasitic capacitance of a prior art TVS circuit with respect to a junction area of a diode. As shown in FIG. 3A, the prior art diode element 100 includes a substrate 11, a field oxide region 12, an N-type well region 13, a P-type drift diffusion region 14, a P-type anode 15 and an N-type cathode 16. FIG. 3B is a graph showing the relationship between the electrostatic withstand voltage and the parasitic capacitance of the prior art TVS circuit with respect to the area of the PN junction of the diode, and the electrostatic withstand voltage and parasitic capacitance thereof will be detailed later than the TVS circuit to which the present invention is applied. .

In view of the above, the present invention is directed to the deficiencies of the prior art described above, and proposes a TVS circuit and a diode element used therein and a manufacturing method thereof to improve the static voltage that the TVS circuit can withstand, and increase the protection and application range of the circuit. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a transient voltage suppressor circuit and a diode element therefor and a method of fabricating the same.

In order to achieve the above object, in one aspect, the present invention provides a transient voltage suppressor circuit for coupling to a protected circuit, thereby limiting the amplitude of a transient voltage input to the protected circuit. The transient voltage suppressor circuit includes: a suppression component having a PN junction for limiting the amplitude of the transient voltage; and at least one diode component coupled between the protected circuit and the suppression component, And the PN junction is oppositely connected to the PN junction; wherein the diode component comprises: a first conductivity type substrate having an upper surface; and a first conductivity type or a second conductivity type well region formed under the upper surface In the substrate; a partitioning region formed in the substrate, the partitioning region being located in the well region as viewed from a top view; a first conductive type anode formed under the upper surface on one side of the partitioning region; and a second conductivity type a cathode formed below the upper surface on the other side of the partition, and the anode and the cathode are separated by the partition; and a plurality of drift diffusion regions formed and connected under the anode or cathode, having the anode Or the same conductivity type of the cathode.

In another aspect, the present invention also provides a diode element for use in a transient voltage suppressor circuit for reversing a suppression element having a PN junction included in the transient voltage suppressor circuit Docking, the diode component used in the transient voltage suppressor circuit includes: a first conductive type substrate having an upper surface; and a first conductive type or second conductive type well region formed on the upper surface In the substrate, a partition is formed in the substrate, and the partition is located in the well region from a top view; a first conductive anode is formed under the upper surface on one side of the partition a second conductive cathode formed under the upper surface on the other side of the partition, and the anode and the cathode are separated by the partition; and a plurality of drift diffusion regions formed and connected under the anode or cathode It has the same conductivity type as the anode or cathode.

In still another aspect, the present invention also provides a method of fabricating a diode component for use in a transient voltage suppressor circuit for use with one of the transient voltage suppressor circuits The suppressing element having the PN junction is reversely butted. The manufacturing method includes: providing a first conductive type substrate having an upper surface; forming a first conductive type or a second conductive type well below the upper surface Forming a partition in the substrate, as viewed from a top view, the partition is located in the well region; forming a first conductive anode on the side of the upper surface of the partition; forming a first a second conductive cathode below the upper surface of the other side of the partition, and the anode and the cathode are separated by the partition; And forming a complex drift diffusion region connected below the anode or cathode, having the same conductivity type as the anode or cathode.

In the above transient voltage suppressor circuit, the suppressing element may comprise a varistor component, a Zener diode, two Zener diodes connected in series, or a metal oxide semiconductor (MOS). element.

In a preferred embodiment, the separation region includes a field oxidation region or a pure semiconductor region.

In a preferred embodiment, the diode elements are plural and arranged on both sides of the suppression element.

The purpose, technical content, features and effects achieved by the present invention will be more readily understood by the detailed description of the embodiments.

The drawings in the present invention are schematic and are mainly intended to represent the process steps and the relationship between the layers, and the shapes, thicknesses, and widths are not drawn to scale.

Referring to Figures 4A and 4B, there is shown a first embodiment of the present invention, and Figure 4A shows a cross-sectional view of a diode element 200 for use in a transient voltage suppressor (TVS) circuit. As shown in FIG. 4A, the diode element 200 includes a substrate 21 having an upper surface 21a. Next, for example, but not limited to, an N-type well region 23 is formed in the substrate 21 under the upper surface 21a. A separation region 22 is then formed in the substrate 21, as viewed from a top view (not shown), the separation region 22 is located in the well region 23; wherein the separation region 22 is, for example, a shallow trench isolation (STI) structure or The local oxidation of silicon (LOCOS) structure is shown. Then, form P separately The anode 25 is below the upper surface 21a of the partition 22 side, and the N-type cathode 26 is below the upper surface 21a of the other side of the partition 22, and the anode 25 and the cathode 26 are separated by the partition 22. A complex drift diffusion region 24 is then formed under the anode 25 and connected to the anode 25, and the drift diffusion region 24 has the same P-type conductivity as the anode 25.

Next, referring to FIG. 4B, a characteristic diagram of the electrostatic withstand voltage and the parasitic capacitance of the TVS circuit to which the diode element 200 of the first embodiment is applied with respect to the junction area of the diode is shown, which is compared with the prior art 3B. It can be seen that in the case where the junction area of the diodes is equal, the capacitances are also substantially equal, but with the TVS circuit of the present invention, the electrostatic withstand voltage is maintained at the measurable limit Max., indicating the TVS circuit to which the present invention is applied. The electrostatic withstand voltage is above the limit Max., while the prior art TVS circuit has a static withstand voltage lower than the limit Max. Comparing the prior art FIG. 3A with the fourth embodiment of the present embodiment, it can be seen that the present embodiment is different from the prior art shown in FIG. 3A. In the present embodiment, a plurality of P-type drift diffusion regions 24 and N-type well regions 23 are present. The contact area increases and the withstand voltage of static electricity increases. The advantages of this arrangement include: in the component specification, since a plurality of impurity concentrations are lower than the drift diffusion region 24 of the anode 25, the transient forward current that the diode component can withstand in the TVS circuit can be improved. The application range of the TVS circuit is increased; in the process, the drift diffusion region 24 can utilize the same process steps in the same substrate 21 as the drift diffusion regions in other high voltage components (not shown), so that the manufacturing cost is hardly increased.

5A and 5B are cross-sectional views showing a second embodiment of the present invention, which is a diode element 300 in a TVS circuit to which the present invention is applied. As shown in the figure, in the present embodiment, the diode element 300 includes a substrate 31, a separation region 32, a P-type well region 33, a plurality of P-type drift diffusion regions 34, and an N-type cathode. 35, with a P-type anode 36. This embodiment is intended to illustrate that In the diode of the present invention, the well region may be the same as the N-type (as in the first embodiment) or the P-type (as in the second embodiment), and only the conductivity type is the same, and the drift diffusion region may be located. Below the P-type anode, it can also be located below the N-type cathode. And the impurity concentration of the drift diffusion region is, for example but not limited to, an impurity concentration lower than an anode or a cathode connected thereto.

Fig. 5B is a graph showing the relationship between the electrostatic withstand voltage and the parasitic capacitance of the TVS circuit to which the diode element 300 of the second embodiment is applied with respect to the junction area of the diode, as compared with the prior art 3B, it can be seen that In the case where the contact area of the polar body is equal, the capacitance is also substantially equal, but the static withstand voltage of the TVS circuit of the present invention is maintained at the measurable limit Max., indicating the electrostatic withstand voltage of the TVS circuit to which the present invention is applied. Above the limit Max.

Figure 6 is a cross-sectional view showing a third embodiment of the present invention, which is a diode element 400 in a TVS circuit to which the present invention is applied. As shown, in the present embodiment, the diode element 400 includes a substrate 41, a pure semiconductor region 42, an N-type well region 43, a plurality of P-type drift diffusion regions 44, P, as shown in the first embodiment. The anode 45 and the N-type cathode 46. This embodiment is intended to illustrate that in the diode of the present invention, not only the field oxide region can be used as the separation region, but also the anode and the cathode can be separated, and the pure semiconductor region can be used as the separation region to separate the anode from the cathode. By pure semiconductor region is meant a region that is substantially close to an intrinsic semiconductor, that is, a semiconductor region that is undoped or lowly doped with impurities.

Referring to Figures 1B-1D and 2, several embodiments of suppressing elements in a TVS circuit to which the present invention is applied are shown. As shown in FIGS. 1B-1D and 2, the suppression element is, for example but not limited to, a varistor element V1 as shown in FIG. 1B, and a Zener diode D2 as shown in FIG. 1C, as shown in FIG. 1D. Shown in series two pairs of Zener diode D2, or the gateless metal as shown in Figure 2 Metal oxide semiconductor (MOS) device Q1.

Please continue to refer to FIG. 2, which shows a preferred arrangement in the TVS circuit to which the present invention is applied. The diode elements Dp and Dn are plural and arranged in the suppression element, here on both sides of the MOS element Q1. Wherein the diode element Dp is for example but not limited to a well region comprising an N-type, and the diode element Dn is for example but not limited to a well region comprising a P-type.

Referring to Figure 7, a top view of the first embodiment of the diode element 200 is shown. As shown in the figure, in the TVS circuit to which the present invention is applied, the complex drift diffusion region 24 of the diode element 200 is viewed from the top view of FIG. 7, and can be arranged as shown in the figure, and can be arranged as an array, and can be The same process steps of drifting the diffusion regions in other high voltage components (not shown) are formed, so that the manufacturing cost can be hardly increased and the ability of the TVS circuit to withstand transient signals can be enhanced.

The present invention has been described with reference to the preferred embodiments thereof, and the present invention is not intended to limit the scope of the present invention. In the same spirit of the invention, various equivalent changes can be conceived by those skilled in the art. For example, other process steps or structures, such as deep well zones, may be added without affecting the primary characteristics of the component; as in the above-described embodiment of the diode component, the method steps for fabricating the diode component may be changed. The region and the drift diffusion region may be formed before the separation region or may be formed after the separation region. The above and other equivalent variations are intended to be covered by the scope of the invention.

1‧‧‧TVS circuit

2‧‧‧protected circuits

3‧‧‧Input and output pads

11,21,31,41‧‧‧substrate

12,22,32‧‧‧Separated area

13,23,33,43‧‧‧ Well Area

24,34,44‧‧‧Drag diffusion zone

15,25,36,45‧‧‧Anode

16,26,35,46‧‧‧ cathode

42‧‧‧Pure semiconductor area

100,200,300,400‧‧‧dipole components

D1, Dn, Dp‧‧‧ diode components

D2‧‧‧Zina diode

Q1‧‧‧MOS components

Figure 1A shows a typical transient voltage suppressor (TVS) circuit 1.

1B-1D shows several kinds of suppression elements in the TVS circuit to which the present invention is applied Example.

Figure 2 shows a preferred arrangement of the diodes in the TVS circuit to which the present invention is applied.

3A-3B are cross-sectional views showing a prior art schematic diagram of a diode element 100 for use in a TVS circuit and a characteristic of electrostatic withstand voltage and parasitic capacitance of a prior art TVS circuit with respect to a junction area of a diode.

Figures 4A and 4B show a first embodiment of the present invention.

Figures 5A and 5B show a second embodiment of the invention.

Figure 6 shows a third embodiment of the present invention.

Figure 7 shows a top view of the first embodiment diode element 200.

21‧‧‧Substrate

21a‧‧‧Upper surface

22‧‧‧Separation zone

23‧‧‧ Well Area

24‧‧‧Drag diffusion zone

25‧‧‧Anode

26‧‧‧ cathode

200‧‧‧ diode components

Claims (10)

A transient voltage suppressor circuit is coupled to a protected circuit for limiting an amplitude of a transient voltage input to the protected circuit, the transient voltage suppressor circuit comprising: a suppression component having a first a PN junction for limiting an amplitude of the transient voltage; and at least one diode component coupled between the protected circuit and the suppression component, and the diode component has a second PN junction Interfacing with the first PN junction; wherein the diode element comprises: a P-type substrate having an upper surface; a P-type or N-type well region formed in the substrate under the upper surface; a partitioning region formed in the substrate, the partitioning region being located in the well region as viewed from a top view; a P-type anode formed under the upper surface on one side of the partitioning region; an N-type cathode formed in a lower surface of the upper side of the partition, and the anode is separated from the cathode by the partition, and the anode or the cathode forms a second PN junction with the well region; and a plurality of drift diffusion regions are formed And connected to the well region below the anode or cathode, There is the same conductivity type as the correspondingly connected anode or cathode, and the impurity concentration of the drift diffusion region is lower than the impurity concentration of the anode or cathode correspondingly connected. The transient voltage suppressor circuit of claim 1, wherein the separation region comprises a field oxide region or a pure semiconductor region. The transient voltage suppressor circuit of claim 1, wherein the suppression component comprises a varistor component, a Zener diode, and two series docking Zener diode, or a gateless metal oxide semiconductor device. The transient voltage suppressor circuit of claim 1, wherein the diode element is plural and arranged on both sides of the suppression element. A diode element for use in a transient voltage suppressor circuit coupled to a suppression element having a first PN junction included in the transient voltage suppressor circuit for use in a transient voltage suppressor circuit The diode component comprises: a P-type substrate having an upper surface; a P-type or N-type well region formed in the substrate under the upper surface; a separation region formed in the substrate Viewing, the partition is located in the well region; a P-type anode is formed below the upper surface on one side of the partition; an N-type cathode is formed below the upper surface on the other side of the partition, And the anode and the cathode are separated by the separation zone, and the anode or the cathode forms a second PN junction with the well region, the second PN junction is opposite to the first PN junction; and the plurality a drift diffusion region formed and connected in the well region below the anode or cathode, having the same conductivity type as the corresponding anode or cathode, and the impurity concentration of the drift diffusion region is lower than the anode or the corresponding connection The impurity concentration of the cathode. A diode element for use in a transient voltage suppressor circuit as described in claim 5, wherein the separation region comprises a field oxide region or a pure semiconductor region. The diode component for use in a transient voltage suppressor circuit according to claim 5, wherein the suppression component comprises a varistor component, a Zener diode, and two Zener diodes connected in series, Or a gateless metal oxide semiconductor component. A method for fabricating a diode element for use in a transient voltage suppressor circuit, the diode element being coupled to a suppression element having a first PN junction included in the transient voltage suppressor circuit, the fabrication The method includes: providing a P-type substrate having an upper surface; forming a P-type or N-type well region in the substrate under the upper surface; forming a separation region in the substrate, viewed from a top view, The separation zone is located in the well zone; forming a P-type anode below the upper surface of the separation zone; forming an N-type cathode below the upper surface of the other side of the separation zone, and the anode and the cathode Separated by the partition, and the anode or the cathode forms a second PN junction with the well region, the second PN junction is opposite to the first PN junction; and a complex drift diffusion region is formed In the well region below the anode or cathode, it has the same conductivity type as the corresponding anode or cathode, and the impurity concentration of the drift diffusion region is lower than the impurity concentration of the anode or cathode correspondingly connected. A method of fabricating a diode element for use in a transient voltage suppressor circuit as described in claim 8 wherein the separation region comprises a field oxide region or a pure semiconductor region. The method for fabricating a diode element for use in a transient voltage suppressor circuit according to claim 8, wherein the diode element is plural and arranged on both sides of the suppression element.