TWI399828B - Method of fabricating transient voltage suppressor (tvs) with changeable avalanche voltage - Google Patents

Description

Transient voltage suppressor manufacturing method capable of changing withstand voltage

The invention relates to a method for manufacturing a transient voltage suppressor capable of changing withstand voltage, in particular to a method for manufacturing a transient voltage suppressor capable of changing withstand voltage applied to a transient voltage suppressor.

In an electric sub-device, the control circuit of the electronic device is often destroyed by the glitch, and the control circuit loses its function. In severe cases, it is more likely to cause electric shock and short circuit of the electric appliance, thereby jeopardizing the personal safety of the user. In the electronic device, an element that suppresses the surge is provided to protect the control circuit from being affected.

The Transient Voltage Suppressor (TVS) is a component with a function of suppressing the surge, which is a diode structure, so the nonlinear ohmic characteristics of the diode can be utilized, so that the stable voltage input control circuit The transient voltage suppressor presents a high impedance state to the control circuit. However, when the input voltage rises instantaneously and a surge occurs, the voltage value of the transient voltage suppressor rapidly drops due to the rapid increase of the voltage, and a short circuit state is formed, thereby providing a low impedance path, thereby using the surge voltage. The current can be conducted away without affecting the control circuit and achieving the effectiveness of the protection control circuit.

Figure 1 is a graph of the voltage-current characteristics of a Zener diode.

Since the transient voltage suppressor works similarly to the Zener diode, for example, the characteristic curve of the transient voltage suppressor can be as shown in Fig. 1, where the input voltage is less than 5 volts for the field emission region, and The input voltage is between 5 volts and 7.5 volts, which is the transition region. When the input voltage is 8 volts, it is the breakdown voltage of the transient voltage suppressor.

From this characteristic graph, when the input voltage of the transient voltage suppressor is greater than 8 volts, a large amount of output current can be stably generated. However, when the input voltage of the transient voltage suppressor is less than 8 volts, the effect of the field emission effect is affected. The instability of the impedance value of the transient voltage suppressor causes leakage current.

According to the specification of the transient voltage suppressor on the market, when the transient voltage suppressor is applied to the transition region and the breakdown voltage respectively, the leakage current value between them is 200 to 500 times higher, so that the transient voltage is made. When the suppressor is applied to the transition region of low voltage, it has the disadvantages of poor reliability and high rated power consumption, which in turn makes the transient voltage suppressor unsuitable for low voltage electronic devices.

The invention is a method for manufacturing a transient voltage suppressor capable of changing withstand voltage, which forms a deep doped layer in a substrate to reduce linear impedance and achieve the effect of improving the power of the transient voltage suppressor.

The invention relates to a method for manufacturing a transient voltage suppressor capable of changing withstand voltage, which is a step of cleaning the etching solution, the mixed acid and the aqua regia during the process of cleaning the substrate to completely remove the oxide layer on the surface of the substrate.

The invention is a method for manufacturing a transient voltage suppressor capable of changing withstand voltage, which is formed by forming an oxide layer of different thickness by changing the heat treatment temperature during the process of heat-treating the substrate, thereby achieving the effect of changing the withstand voltage, and then applying To reduce the leakage current in the transition region and the field emission region.

The present invention is a method for manufacturing a transient voltage suppressor capable of changing withstand voltage, which is added to a chlorine-containing gas during heat treatment of a substrate, thereby forming a chlorine-containing oxide insulating layer having a stable charge effect.

In order to achieve the above effects, the present invention provides a method for fabricating a transient voltage suppressor capable of changing withstand voltage, comprising the steps of: providing a substrate having: a pair of deeply doped layers formed by diffusion diffusion The two sides of the substrate, and the deep doped layer is composed of a first type deep doped layer and a second type deep doped layer, and a first type original substrate layer is formed between the deep doped layers; the patterned substrate Etching the second type deep doped layer and the first type original substrate layer to penetrate the second type deep doped layer and form at least one trench on the first type original substrate layer; cleaning the substrate, including the following Step: soaking the substrate in an etching solution, and the etching solution is composed of hydrofluoric acid and deionized water in a first solution volume ratio; cleaning the substrate with a mixed acid solution, and mixing the acid solution with nitric acid, hydrofluoric acid And the acetic acid solution is composed of a second solution volume ratio; and the substrate is immersed in an aqueous solution of the king, and the aqueous solution of the king is composed of nitric acid, hydrochloric acid and deionized water in a volume ratio of the third solution; Forming an oxidized insulating layer on the surface of the trench, comprising the steps of: heat-treating at a first temperature for 3 minutes in a nitrogen atmosphere; heat-treating at a second temperature in a mixed nitrogen, a chlorine-containing gas, and an oxygen atmosphere; Minute; heat treatment at a third temperature for 90 minutes in a mixed nitrogen, chlorine gas, and oxygen atmosphere; heat treatment at a fourth temperature for 2 minutes in a mixed nitrogen and oxygen atmosphere; and a fifth temperature in a nitrogen atmosphere Heat treatment for 10 seconds; and forming a pair of metal electrodes respectively covering the surface of the deep doped layer and exposing the oxidized insulating layer to the outside of the metal electrode.

With the implementation of the present invention, at least the following advancements can be achieved:

First, the temperature of the heat treatment is adjusted to change the withstand voltage of the transient voltage suppressor, thereby reducing the leakage current of the transient voltage suppressor applied to the low voltage.

Second, since the transient voltage suppressor is improved when the low voltage is applied, the reliability of the transient voltage suppressor in low voltage applications and the reduction of the rated power consumption can be achieved.

In order to make those skilled in the art understand the technical content of the present invention and implement it, and according to the disclosure, the patent scope and the drawings, the related objects and advantages of the present invention can be easily understood by those skilled in the art. The detailed features and advantages of the present invention will be described in detail in the embodiments.

Fig. 2 is a flow chart showing an embodiment of a method for manufacturing a transient voltage suppressor S100 capable of changing withstand voltage. Fig. 3 is a cross-sectional view showing a substrate 10 of the present invention. Figure 4 is a cross-sectional view of a substrate 10 having a trench 14 of the present invention. Fig. 5 is a flow chart showing an embodiment of a step S30 of cleaning a substrate of the present invention. Fig. 6 is a view showing a flow chart of a step S40 of heat-treating the substrate of the present invention. Figure 7 is a cross-sectional view showing a substrate 10 having an oxidized insulating layer 15 of the present invention. Figure 8 is a cross-sectional view of a transient voltage suppressor of the present invention.

As shown in FIG. 2, this embodiment is a transient voltage suppressor manufacturing method S100 capable of changing withstand voltage, comprising the steps of: providing a substrate S10; patterning the substrate S20; cleaning the substrate S30; heat treating the substrate S40; And forming a pair of metal electrodes S50.

A substrate S10 is provided. As shown in FIG. 3, the substrate 10 can be a germanium substrate, and a pair of deep doped layers 11 and 12 are formed on both sides of the substrate 10 by drive-in diffusion. . The transient voltage suppressor fabricated using the substrate 10 having the deep doped layers 11, 12 can have a lower linear impedance, thereby achieving the effect of reducing the rated power consumption. Further, the deep doped layers 11 and 12 of the substrate 10 include a first type deep doped layer 11 and a second type deep doped layer 12, and the first type deep doped layer 11 and the second type deep doped layer 12 A first type of original substrate layer 13 is formed again.

For example, when the transient voltage suppressor is applied to suppress negative surges, the first type deep doped layer 11 may be an N type deep doped layer, and the second type deep doped layer 12 may be a P. The deep doped layer is formed, and the first type original substrate layer 13 is an N-type original substrate layer. Conversely, when the first type deep doped layer 11 is a P type deep doped layer, the transient voltage suppressor can be applied to suppress the positive glitch, and the second type deep doped layer 12 can be a N. The deep-doped layer is formed, and the first-type original substrate layer 13 is a P-type original substrate layer.

The patterned substrate S20 is formed by patterning the surface of the second type deep doping layer 12 of the substrate 10 by using the current lithography exposure technique, and then etching the pattern of the surface of the second type deep doping layer 12 by etching. The depth of the etch is as shown in FIG. 4, which penetrates the second type deep doped layer 12 and forms at least one trench 14 on the first type original substrate layer 13.

Cleaning the substrate S30: As shown in FIG. 5, the cleaning substrate step S30 can be further subdivided into the following steps: soaking the substrate in an etching solution S31; cleaning the substrate S32 with a mixed acid solution; and soaking the substrate in an aqueous solution of S33.

Soaking the substrate in an etching solution S31: Since the substrate 10 is exposed to the air, the surface of the substrate 10 is likely to have an excess oxide layer, and the etching solution can be used to remove excess oxide layer on the surface of the substrate 10, and the etching solution is The hydrofluoric acid and deionized water are combined in a first solution volume ratio, and the first solution volume ratio may be 1:4.

The substrate S32 is cleaned by using a mixed acid solution: since the surface of the substrate 10 after removing the oxide layer by the etching solution is a rough uneven surface, the surface of the substrate 10 can be cleaned using a mixed acid solution, and the surface of the substrate 10 can be smoothed and mixed. The acid solution is composed of nitric acid, hydrofluoric acid and acetic acid solution in a second solution volume ratio, and the second solution volume ratio may be 12:1:6.

Soaking the substrate in a king aqueous solution S33: In order to ensure that the surface oxide layer of the substrate 10 has been completely removed, and to avoid affecting the quality of the subsequent process, the oxide layer on the surface of the substrate 10 can be removed again by using the aqueous solution of the king, so that the oxide layer on the surface of the substrate 10 can be It is completely removed, and the aqueous solution of the king is composed of nitric acid, hydrochloric acid and deionized water in a third solution volume ratio, and the third solution volume ratio can be 7:6:30.

Heat-treating the substrate S40: as shown in FIGS. 6 and 7, heat-treating the substrate 10 to form an oxidized insulating layer 15 on the surface of the trench 14 of the substrate 10, and the heat-treating substrate step S40 may also be subdivided into the following steps: Heat treatment at a first temperature for 3 minutes in a nitrogen atmosphere; heat treatment at a second temperature for 17 minutes in a mixed nitrogen, a chlorine-containing gas, and an oxygen atmosphere; in a mixed nitrogen, chlorine-containing gas, and oxygen atmosphere Heat treatment at a third temperature for 90 minutes S43; heat treatment at a fourth temperature for 2 minutes S44 in a mixed nitrogen and oxygen atmosphere; and heat treatment at a fifth temperature for 10 seconds S45 under a nitrogen atmosphere.

As shown in FIG. 7, in the process of heat-treating the substrate S40, each of the above steps is continuously and sequentially operated, so that the surface of the trench 14 of the substrate 10 is subjected to heat treatment to form the oxidized insulating layer 15, and the process of heat-treating the substrate 10 is performed. The first temperature system may be 800 ° C, the second temperature system may be 950 ° C, the third temperature and the fourth temperature may be between 1000 ° C and 1200 ° C, and the fifth temperature system may be 800 ° C.

As shown in FIG. 6, when the substrate 10 is heat-treated at a third temperature for 90 minutes in a mixed nitrogen gas, a chlorine-containing gas, and oxygen, the step S43 is performed, and the fourth temperature is heat-treated for 2 minutes in an atmosphere of mixing nitrogen and oxygen. By changing the third temperature and the fourth temperature, the thickness of the oxidized insulating layer 15 on the substrate 10 is increased as the temperature of the heat treatment rises, and the transient voltage suppressor has a high withstand voltage characteristic, that is, This allows the transient voltage suppressor to have a higher breakdown voltage. Conversely, when a lower heat treatment temperature is selected, a transient voltage suppressor having a lower withstand voltage and a breakdown voltage can be formed.

Since the breakdown voltage of the transient voltage suppressor can be changed by adjusting the thickness of the oxide insulating layer 15, the transient voltage suppressor can be reduced when the transient voltage suppressor is applied to a low voltage device, for example, 3 volts to 6 volts. The breakdown voltage, and because of the low leakage current when the input voltage is a breakdown voltage, can greatly improve the leakage current phenomenon of the transient voltage suppressor in the transition region, and increase the reliability of the transient voltage suppressor applied to the low voltage. Sex.

Further, during the heat treatment of the substrate step S40, the fluidity of the oxygen can be increased by adding nitrogen gas to increase the oxygen exchange rate during the heat treatment, and the oxide insulation can be more uniformly and rapidly formed on the surface of the trench 14 of the substrate 10. Layer 15 (as shown in Figure 7).

The chlorine-containing gas system used in the heat treatment process may be dichloroethylene gas, methylene chloride gas or hydrochloric acid gas, and the chlorine molecule in the chlorine-containing gas has the functions of stabilizing charge and improving stability, so it can be used as a stabilizer. And the process success rate of the oxidized insulating layer 15 in the transient voltage suppressor manufacturing method S100 can be improved.

Further, since the chlorine-containing gas is added during the heat treatment of the substrate S40, the generated oxidized insulating layer 15 also contains chlorine molecules, so that the oxidized insulating layer 15 can have a function of stabilizing charges and can improve the insulating performance of the oxidized insulating layer 15.

Forming a pair of metal electrodes S50: as shown in FIG. 8, the substrate 10 is metallized so that a pair of metal electrodes 16 are respectively formed on the first type deep doped layer 11 of the substrate 10 and the second type depth The surface of the layer 12 is doped, and the oxidized insulating layer 15 is exposed outside the metal electrode 16 to form an electrode of the transient voltage suppressor, and the material of the metal electrode 16 may be a metal having a high conductivity, such as gold. , nickel...etc.

The embodiments are described to illustrate the features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the present invention and to implement the present invention without limiting the scope of the present invention. Equivalent modifications or modifications made by the spirit of the disclosure should still be included in the scope of the claims described below.

10. . . Substrate

11. . . First type deep doped layer

12. . . Second type deep doped layer

13. . . First type original substrate layer

14. . . Trench

15. . . Oxidized insulating layer

16. . . Metal electrode

Figure 1 is a graph of the voltage-current characteristics of a Zener diode.

Fig. 2 is a flow chart showing an embodiment of a method for manufacturing a transient voltage suppressor capable of changing withstand voltage according to the present invention.

Figure 3 is a cross-sectional view showing a substrate of the present invention.

Figure 4 is a cross-sectional view of a substrate having a trench of the present invention.

Figure 5 is a flow chart showing an embodiment of a step of cleaning a substrate of the present invention.

Figure 6 is a flow chart showing a process of the step of heat-treating the substrate of the present invention.

Figure 7 is a cross-sectional view showing a substrate having an oxidized insulating layer of the present invention.

Figure 8 is a cross-sectional view of a transient voltage suppressor of the present invention.

S10. . . Providing a substrate

S20. . . Patterned substrate

S30. . . Cleaning substrate

S40. . . Heat treated substrate

S50. . . Forming a pair of metal electrodes

Claims (16)

A method for manufacturing a transient voltage suppressor capable of changing withstand voltage, comprising the steps of: providing a substrate having: a pair of deeply doped layers formed on both sides of the substrate by diffusion diffusion, and The deep doped layer is composed of a first type deep doped layer and two second type deep doped layers, and a first type original substrate layer is formed between the pair of deep doped layers; the substrate is patterned. Etching the second type deep doped layer and the first type original substrate layer to penetrate the second type deep doped layer and form at least one trench on the first type original substrate layer; cleaning the substrate, The method comprises the steps of: immersing the substrate in an etching solution, and the etching solution is composed of hydrofluoric acid and deionized water in a first solution volume ratio; cleaning the substrate with a mixed acid solution, and the mixed acid solution Is composed of nitric acid, hydrofluoric acid and acetic acid solution in a second solution volume ratio; and soaking the substrate in an aqueous solution of a king, and the aqueous solution of the king is composed of nitric acid, hydrochloric acid and deionized water in a third solution volume ratio ;heat The substrate is formed to form an oxidized insulating layer on the surface of the trench, comprising the steps of: heat treating at a first temperature for 3 minutes in a nitrogen atmosphere; and mixing the nitrogen gas, a chlorine gas and an oxygen gas And heat-treating at a second temperature for 17 minutes; heat-treating at a third temperature for 90 minutes in an environment where the nitrogen gas, the chlorine-containing gas and the oxygen are mixed; and heat-treating at a fourth temperature in an environment where the nitrogen gas and the oxygen are mixed; And a heat treatment at a fifth temperature for 10 seconds in the nitrogen atmosphere; and forming a pair of metal electrodes respectively covering the surfaces of the pair of deep doped layers, and exposing the oxidized insulating layer to the pair Outside the metal electrode. The method for manufacturing a transient voltage suppressor according to claim 1, wherein the first type deep doped layer is an N type deep doped layer, and the second type deep doped layer is a P A deep doped layer, and the first type of original substrate layer is an N-type original substrate layer. The method of fabricating a transient voltage suppressor according to claim 1, wherein the first type deep doped layer is a P type deep doped layer, and the second type deep doped layer is a N A deep doped layer, and the first type of original substrate layer is a P-type original substrate layer. The method of manufacturing a transient voltage suppressor according to claim 1, wherein the first solution volume ratio is 1:4. The method of manufacturing a transient voltage suppressor according to claim 1, wherein the second solution volume ratio is 12:1:6. The method of manufacturing a transient voltage suppressor according to claim 1, wherein the third solution volume ratio is 2:6:16. The method of manufacturing a transient voltage suppressor according to claim 1, wherein the first temperature system is 800 °C. The method of manufacturing a transient voltage suppressor according to claim 1, wherein the second temperature system is 950 °C. The method of manufacturing a transient voltage suppressor according to claim 1, wherein the third temperature system is from 1000 ° C to 1200 ° C. The method of manufacturing a transient voltage suppressor according to claim 1, wherein the fourth temperature system is from 1000 ° C to 1200 ° C. The method of manufacturing a transient voltage suppressor according to claim 1, wherein the fifth temperature system is 800 °C. The method of manufacturing a transient voltage suppressor according to claim 1, wherein the chlorine-containing gas system is a dichloroethylene gas. The method of manufacturing a transient voltage suppressor according to claim 1, wherein the chlorine-containing gas system is dichloromethane gas. The method of manufacturing a transient voltage suppressor according to claim 1, wherein the chlorine-containing gas system is hydrochloric acid gas. The method of manufacturing a transient voltage suppressor according to claim 1, wherein the material of the pair of metal electrodes is gold. The method of manufacturing a transient voltage suppressor according to claim 1, wherein the material of the pair of metal electrodes is nickel.