阅读说明：本技术 一种半导体开关器件及其制作方法 (Semiconductor switch device and manufacturing method thereof ) 是由 王凡 于 2018-07-17 设计创作，主要内容包括：本发明提供一种半导体开关器件及其制作方法,包括：P型基底、N型阱区、P型阱区、N型漂移区、栅极结构及侧墙、N型源区、P型导电区、介质层及源区电极。所述P型导电区形成于所述N型源区的下部,所述介质层中形成有源区接触窗口,所述源区接触窗口显露的所述N型源区的中部区域反型形成P型接触区,所述P型接触区的两侧均保留有部分所述N型源区。本发明相比于传统工艺能节省一次掩膜的制作,可有效降低工艺成本。本发明可以有效降低器件的导通电阻,提高器件的驱动电流。本发明可以有效避免由于latchup路径电压过高而导致半导体开关器件的lachtup效应(闩锁效应)的产生。(The invention provides a semiconductor switch device and a manufacturing method thereof, comprising the following steps: the semiconductor device comprises a P-type substrate, an N-type well region, a P-type well region, an N-type drift region, a grid structure, a side wall, an N-type source region, a P-type conductive region, a dielectric layer and a source region electrode. The P-type conductive region is formed at the lower part of the N-type source region, an active region contact window is formed in the dielectric layer, the middle region of the N-type source region exposed by the active region contact window is inverted to form a P-type contact region, and parts of the N-type source region are reserved on two sides of the P-type contact region. Compared with the traditional process, the invention can save the manufacture of a mask and effectively reduce the process cost. The invention can effectively reduce the on-resistance of the device and improve the driving current of the device. The invention can effectively avoid the generation of the latch-up effect (latch-up effect) of the semiconductor switching device caused by overhigh latchup path voltage.)

1. A method of fabricating a semiconductor switching device, the method comprising the steps of:

1) providing a P-type substrate;

2) forming an N-type well region in the P-type substrate;

3) forming P-type well regions arranged at intervals in the N-type well region and an N-type drift region between the P-type well regions;

4) manufacturing a grid structure, wherein the grid structure comprises a first grid unit and a second grid unit which are spaced and cross between the N-type well region and the P-type well region;

5) performing N-type ion implantation by taking the grid structure as a mask so as to form an N-type source region in the P-type well region;

6) manufacturing a side wall structure on the side face of the grid structure, and then performing P-type ion implantation by taking the grid structure and the side wall structure as masks to form a P-type conductive region on the lower part of the N-type source region, wherein the width of the P-type conductive region is smaller than that of the N-type source region;

7) forming a dielectric layer on the surface of a device, forming a source region contact window in the dielectric layer, exposing the middle region of the N-type source region through the source region contact window, and performing P-type ion implantation based on the source region contact window by taking the dielectric layer as a mask so that the exposed middle region of the N-type source region is inverted to form a P-type contact region, wherein the P-type contact region is connected with the P-type conductive region, and parts of the N-type source region are reserved on two sides of the P-type contact region;

8) and filling a conductive material in the source region contact window to form a source region electrode.

2. The method for manufacturing a semiconductor switching device according to claim 1, wherein: in the step 6), the ratio of the width of the source region contact window to the width of the N-type source region is 0.4: 1-1: 1.

3. The method for manufacturing a semiconductor switching device according to claim 1, wherein: the dosage of the P type ion implantation for forming the P type conduction region in the step 6) is greater than that of the N type ion implantation for forming the N type source region in the step 5), wherein the dosage of the P type ion implantation for forming the P type conduction region in the step 6) is not less than 5e15/cm²。

4. The method for manufacturing a semiconductor switching device according to claim 1, wherein: the dosage of the P-type ion implantation for forming the P-type contact region in the step 6) is greater than that of the N-type ion implantation for forming the N-type source region in the step 5), wherein the dosage of the N-type ion implantation for forming the N-type source region in the step 5) is 10¹⁵/cm²Order of magnitude, the dosage of the P-type ion implantation for forming the P-type contact region in the step 6) is 10¹⁶/cm²An order of magnitude.

5. The method for manufacturing a semiconductor switching device according to claim 1, wherein: the N-type source region extends in a long strip shape, and the source region contact windows are arranged at intervals along the extending direction of the N-type source region.

6. The method for manufacturing a semiconductor switching device according to claim 1, wherein: the step 1) further comprises a step of forming an STI (shallow trench isolation) or LOCOS (local area oxidation of silicon) isolation region in the P-type epitaxial layer, wherein the STI or LOCOS isolation region is positioned between the first gate unit and the second gate unit which are manufactured subsequently.

7. The method for manufacturing a semiconductor switching device according to claim 6, wherein: the N-type drift region surrounds the STI isolation region or the LOCOS isolation region.

8. The method for manufacturing a semiconductor switching device according to claim 1, wherein: the P-type base comprises a P-type substrate, and the doping concentration of the P-type substrate is 1e 15-1 e16/cm³The doping concentration of the N-type well region is 1e 15-1 e16/cm³And the doping concentration of the N-type well region is greater than that of the P-type substrate, and the doping concentration of the P-type well region is 1e 17-1 e18/cm³。

9. The method for manufacturing a semiconductor switching device according to claim 1, wherein: the P-type substrate comprises a P-type substrate and a P-type epitaxial layer formed on the P-type substrate, the N-type trap region is formed in the P-type epitaxial layer, the doping concentration of the P-type substrate is greater than that of the P-type epitaxial layer, and the doping concentration of the P-type epitaxial layer is 1e 15-1 e16/cm³The doping concentration of the P-type substrate is 1e 17-1 e18/cm³。

10. A semiconductor switching device characterized in that: the method comprises the following steps:

a P-type substrate;

the N-type well region is formed in the P-type substrate;

the P-type well regions are arranged at intervals and formed in the N-type well regions;

the N-type drift regions are formed between the P-type well regions at intervals;

the grid structure comprises a first grid unit and a second grid unit which are spaced and cross between the N-type well region and the P-type well region;

the N-type source region is formed in the P-type well region on the outer side of the first gate unit and the second gate unit;

the side wall structure is positioned on the side face of the grid structure;

the P-type conducting region is formed at the lower part of the N-type source region, and the width of the P-type conducting region is smaller than that of the N-type source region;

the dielectric layer covers the surface of the device, an active region contact window is formed in the dielectric layer, the active region contact window exposes the middle region of the N-type source region, the middle region of the N-type source region exposed by the active region contact window is inverted to form a P-type contact region, the P-type contact region is connected with the P-type conductive region, and partial N-type source regions are reserved on two sides of the P-type contact region; and

and the conductive material is filled in the source region contact window to form a source region electrode.

11. The semiconductor switching device according to claim 10, wherein: the ratio of the width of the source region contact window to the width of the N-type source region is 0.4: 1-1: 1.

12. The semiconductor switching device according to claim 10, wherein: the P-type ion doping concentration of the P-type conduction region is greater than the N-type ion doping concentration of the N-type source region, wherein the P-type ion doping concentration of the P-type conduction region is not less than 5e17/cm³。

13. The semiconductor switching device according to claim 10, wherein: the P-type ion doping concentration of the P-type contact region is greater than the N-type ion doping concentration of the N-type source region, wherein the N-type ion doping concentration of the N-type source region is 10¹⁷/cm³The order of magnitude, the P-type ion doping concentration of the P-type contact region is 10¹⁸/cm³An order of magnitude.

14. The semiconductor switching device according to claim 10, wherein: the N-type source region extends in a long strip shape, and the source region contact windows are arranged at intervals along the extending direction of the N-type source region.

15. The semiconductor switching device according to claim 10, wherein: an STI isolation region or a LOCOS isolation region is also formed in the N-type well region between the first gate unit and the second gate unit.

16. The semiconductor switching device according to claim 15, wherein: the N-type drift region surrounds the STI isolation region or the LOCOS isolation region, and the doping concentration of the N-type drift region is 1e 16-1 e17/cm³。

17. The semiconductor switching device according to claim 10, wherein: the P-type base comprises a P-type substrate, and the doping concentration of the P-type substrate is 1e 15-1 e16/cm³The doping concentration of the N-type well region is 1e 15-1 e16/cm³And the doping concentration of the N-type well region is greater than that of the P-type substrate, and the doping concentration of the P-type well region is 1e 17-1 e18/cm³。

18. The semiconductor switching device according to claim 10, wherein: the P-type substrate comprises a P-type substrate and a P-type epitaxial layer formed on the P-type substrate, the N-type trap region is formed in the P-type epitaxial layer, the doping concentration of the P-type substrate is greater than that of the P-type epitaxial layer, and the doping concentration of the P-type epitaxial layer is 1e 15-1 e16/cm³The doping concentration of the P-type substrate is 1e 17-1 e18/cm³。

Technical Field

The invention relates to the field of integrated circuit design and manufacture, in particular to a semiconductor switch device and a manufacturing method thereof.

Background

With the technological progress and social development, portable devices such as mobile phones, notebook computers, MP3 players, PDAs, handheld game consoles, digital video cameras, etc. have become more and more popular, many of these products are powered by lithium ion batteries, which are divided into primary batteries and secondary batteries, and currently, non-rechargeable primary lithium batteries are mainly used in some portable electronic products with lower power consumption, while rechargeable secondary batteries, i.e., lithium ion batteries, are used in electronic products with higher power consumption, such as notebook computers, mobile phones, PDAs, digital cameras, etc.

Compared with nickel-cadmium and nickel-hydrogen batteries, the lithium ion battery has the following advantages: 1) the voltage is high, and the voltage of a single lithium ion battery can reach 3.6V, which is much higher than the voltage of 1.2V of nickel-cadmium and nickel-hydrogen batteries. 2) The capacity density is large, and is 1.5 to 2.5 times of that of a nickel-hydrogen battery or a nickel-cadmium battery. 3) The charge retention capacity is strong (i.e. self-discharge is small), and the capacity loss is small after the material is placed for a long time. 4) The service life is long, and the cycle life can reach more than 500 times in normal use. 5) Has no memory effect, does not need to empty the residual electric quantity before charging, and is convenient to use.

Because of the chemical characteristics of lithium ion batteries, in the normal use process, the lithium ion batteries perform chemical positive reaction in which electric energy and chemical energy are converted mutually, but under certain conditions, such as overcharge, overdischarge and overcurrent, the chemical side reaction can be caused in the batteries, after the side reaction is intensified, the performance and the service life of the batteries can be seriously influenced, a large amount of gas can be generated, and the internal pressure of the batteries is rapidly increased and then explodes to cause a safety problem.

A typical li-ion battery protection circuit is schematically shown in fig. 1a, and the protection circuit is composed of two MOSFETs (V1, V2) and a control IC (N1) with the addition of resistive-capacitive elements. The control IC is responsible for monitoring the voltage and the loop current of the battery and controlling the grids of two MOSFETs, the MOSFETs play a role of a switch in the circuit and respectively control the on and off of a charging loop and a discharging loop, C3 is a delay capacitor, the circuit has the functions of overcharge protection, overdischarge protection, overcurrent protection and short circuit protection, and the working principle analysis is as follows:

1) in normal state, the pins "CO" and "DO" of N1 output high voltage, both MOSFETs are in conduction state, the battery can be charged and discharged freely, and the on resistance of the MOSFETs is small, usually less than 30 milliohm, so the performance of the circuit is affected little by its on resistance. The consumption current of the protection circuit in this state is of the order of μ a, typically less than 7 μ a.

2) The lithium ion battery requires a constant current/constant voltage charging mode, the lithium ion battery is charged by the constant current at the initial charging stage, the voltage can rise to 4.2V (some batteries require a constant voltage value of 4.1V according to different anode materials) along with the charging process, and the lithium ion battery is converted into the constant voltage charging mode until the current is smaller and smaller. When the battery is charged, if the charger circuit is out of control, the battery voltage can continue to be charged with constant current after exceeding 4.2V, and at the moment, the battery voltage can still continue to rise, and when the battery voltage is charged to exceed 4.3V, the chemical side reaction of the battery is intensified, so that the battery can be damaged or safety problems can occur. In the battery with the protection circuit, when the control IC detects that the battery voltage reaches 4.28V (the value is determined by the control IC, different ICs have different values), the 'CO' pin of the control IC is changed from high voltage to zero voltage, so that V2 is changed from on to off, thereby cutting off the charging loop, and the charger can not charge the battery any more, thereby playing the role of overcharge protection. At this time, due to the existence of the body diode VD2 of the V2, the battery can discharge the external load through the diode. Between the control IC detecting that the battery voltage exceeds 4.28V and sending the signal of turning off V2, there is a delay time, the length of which is determined by C3 and is usually set to about 1 second, so as to avoid misjudgment due to interference.

3) When the battery discharges to the external load, the voltage of the battery is gradually reduced along with the discharging process, and when the voltage of the battery is reduced to 2.5V, the capacity of the battery is completely discharged, and at the moment, if the battery is allowed to continue to discharge to the load, the battery is permanently damaged. When the control IC detects that the battery voltage is lower than 2.3V (the value is determined by the control IC, and different ICs have different values) during the discharging process of the battery, the "DO" pin of the control IC changes from high voltage to zero voltage, so that V1 is changed from on to off, thereby cutting off the discharging loop, and the battery cannot discharge the load any more, thereby playing the role of over-discharging protection. At this time, due to the presence of the body diode VD1 of V1, the charger can charge the battery through the diode. Since the battery voltage can not be reduced in the over-discharge protection state, the consumption current of the protection circuit is required to be extremely small, and at this time, the control IC enters a low power consumption state, and the power consumption of the whole protection circuit is less than 0.1 mua. There is also a delay time between the battery voltage detected by the control IC being lower than 2.3V and the signal of turning off V1, the length of the delay time is determined by C3, and is usually set to about 100 ms, so as to avoid misjudgment due to interference.

4) Due to the chemical characteristics of lithium ion batteries, battery manufacturers specify that the discharge current of the lithium ion batteries cannot exceed 2C (C ═ battery capacity/hour) at maximum, and when the batteries are discharged at a current exceeding 2C, permanent damage to the batteries or safety problems may occur. When the battery discharges to the load normally, when the discharging current passes through 2 MOSFETs connected in series, a voltage is generated at two ends of the MOSFET due to the on-resistance of the MOSFET, the voltage value U is I RDS 2, RDS is the on-resistance of a single MOSFET, a 'V' -pin on a control IC detects the voltage value, if the load is abnormal due to some reason, the loop current is increased, when the loop current is large to enable U to be more than 0.1V (the value is determined by the control IC, different ICs have different values), a 'DO' pin is converted from high voltage to zero voltage, and V1 is converted from on to off, so that the discharging loop is cut off, the current in the loop is zero, and the overcurrent protection function is achieved. There is also a delay time between the control IC detecting the overcurrent occurrence and the signal of turning off V1, the length of the delay time is determined by C3, usually about 13 ms, to avoid misjudgment due to interference. In the above control process, it is understood that the magnitude of the overcurrent detection value depends not only on the control value of the control IC but also on the on-resistance of the MOSFET, and the larger the on-resistance of the MOSFET is, the smaller the overcurrent protection value is for the same control IC.

5) When the current of the loop is large enough to make U >0.9V (the value is determined by the control IC, different ICs have different values) in the process of discharging the battery to the load, the control IC judges that the load is short-circuited, the DO pin of the control IC is quickly changed from high voltage to zero voltage, and V1 is changed from on to off, so that the discharging loop is cut off, and the short-circuit protection effect is achieved. The delay time for short circuit protection is extremely short, typically less than 7 microseconds. The working principle of the method is similar to that of overcurrent protection, and only the judgment method is different, and the protection delay time is different.

Besides the control IC, the circuit also has an important element, namely MOSFET, which plays the role of a switch in the circuit, and the on-resistance of the MOSFET has the influence on the performance of the battery because the MOSFET is directly connected in series between the battery and an external load.

Two MOSFETs for lithium battery protection are currently implemented by using Trench VDMOS (Trench vertical double-diffused metal oxide semiconductor field effect transistor). The VDMOS has the advantages of high channel density and effective reduction of channel resistance. The lithium battery protection VDMOS needs to lead out a source electrode, a P-type contact region needs to be formed in an N-type source region in order to ensure the current lead-out of the source electrode, and the conventional manufacturing of the N-type source region and the P-type contact region generally comprises the following steps: 1) manufacturing a first gate structure 101; 2) a first mask layer is manufactured (the first mask layer shields a 103 area in the figure), and N-type ion implantation is carried out to form an N-type source area 102; 3) a second mask layer is formed to cover the region 102 in the figure, and P-type ion implantation is performed to form P-type contact regions 103, so as to form N-type source regions 102 and P-type contact regions 103 which are alternately arranged, as shown in fig. 1 b.

The lithium battery protection VDMOS has the following disadvantages:

first, at least two mask layers are required to form the N-type source region 102 and the P-type contact region 103, which increases the process difficulty and the process cost.

Secondly, the P-type contact region 103 occupies the entire width of the N-type source region 102, so that current cannot flow in the region of the P-type contact region 103 in the process of conducting the device, the conducting internal resistance of the device is increased, and the driving current is reduced.

More importantly, the existing VDMOS for lithium battery protection has a relatively serious lachtup effect, namely latch-up effect, which is caused by parasitic transistors, and the effect can cause large current at low voltage, which not only can cause disorder of circuit function, but also can cause a short circuit between a power supply and a ground wire, and cause permanent damage to a chip.

Based on the above, it is necessary to provide a semiconductor switch device and a method for manufacturing the same, which can effectively reduce the process cost, effectively reduce the on-resistance of the device, increase the driving current of the device, and effectively prevent the latch-up effect.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a semiconductor switch device and a method for manufacturing the same, which are used to solve the problems of the prior art that the drift region of the MOSFET for lithium battery protection has a large internal resistance and a large area.

To achieve the above and other related objects, the present invention provides a method for fabricating a semiconductor switching device, the method comprising the steps of: 1) providing a P-type substrate; 2) forming an N-type well region in the P-type substrate; 3) forming P-type well regions arranged at intervals in the N-type well region and an N-type drift region between the P-type well regions; 4) manufacturing a grid structure, wherein the grid structure comprises a first grid unit and a second grid unit which are spaced and cross between the N-type well region and the P-type well region; 5) performing N-type ion implantation by taking the grid structure as a mask so as to form an N-type source region in the P-type well region; 6) manufacturing a side wall structure on the side face of the grid structure, and then performing P-type ion implantation by taking the grid structure and the side wall structure as masks to form a P-type conductive region on the lower part of the N-type source region, wherein the width of the P-type conductive region is smaller than that of the N-type source region; 7) forming a dielectric layer on the surface of a device, forming a source region contact window in the dielectric layer, exposing the middle region of the N-type source region through the source region contact window, and performing P-type ion implantation based on the source region contact window by taking the dielectric layer as a mask so that the exposed middle region of the N-type source region is inverted to form a P-type contact region, wherein the P-type contact region is connected with the P-type conductive region, and parts of the N-type source region are reserved on two sides of the P-type contact region; 8) and filling a conductive material in the source region contact window to form a source region electrode.

Preferably, in the step 6), the ratio of the width of the source region contact window to the width of the N-type source region is between 0.4:1 and 1: 1.

Preferably, the dosage of the P-type ion implantation for forming the P-type conductive region in step 6) is greater than that of the N-type ion implantation for forming the N-type source region in step 5), wherein the dosage of the P-type ion implantation for forming the P-type conductive region in step 6) is not less than 5e15/cm²。

Preferably, the dosage of the P-type ion implantation for forming the P-type contact region in step 6) is greater than that of the N-type ion implantation for forming the N-type source region in step 5), wherein the dosage of the N-type ion implantation for forming the N-type source region in step 5) is 10¹⁵/cm²Order of magnitude, the dosage of the P-type ion implantation for forming the P-type contact region in the step 6) is 10¹⁶/cm²On the order of magnitude.

Preferably, the N-type source region extends in a long strip shape, and the source region contact windows are arranged at intervals along the extending direction of the N-type source region.

Preferably, step 1) further includes a step of forming an STI isolation region or a LOCOS isolation region in the P-type epitaxial layer, where the STI isolation region or the LOCOS isolation region is located between the first gate unit and the second gate unit which are subsequently manufactured.

Preferably, the N-type drift region surrounds the STI isolation region or the LOCOS isolation region.

Preferably, the P-type base comprises a P-type substrate, and the doping concentration of the P-type substrate is 1e 15-1 e16/cm³The doping concentration of the N-type well region is 1e 15-1 e16/cm³And the doping concentration of the N-type well region is greater than that of the P-type substrate, and the doping concentration of the P-type well region is 1e 17-1 e18/cm³。

Preferably, the P-type substrate comprises a P-type substrate and a P-type epitaxial layer formed on the P-type substrate, the N-type well region is formed in the P-type epitaxial layer, and the doping concentration of the P-type substrate is greater than that of the P-type epitaxial layer, wherein the doping concentration of the P-type epitaxial layer is 1e 15-1 e16/cm³The doping concentration of the P-type substrate is 1e 17-1 e18/cm³。

The present invention also provides a semiconductor switching device comprising: a P-type substrate; the N-type well region is formed in the P-type substrate; the P-type well regions are arranged at intervals and formed in the N-type well regions; the N-type drift regions are formed between the P-type well regions at intervals; the grid structure comprises a first grid unit and a second grid unit which are spaced and cross between the N-type well region and the P-type well region; the N-type source region is formed in the P-type well region on the outer side of the first gate unit and the second gate unit; the side wall structure is positioned on the side face of the grid structure; the P-type conducting region is formed at the lower part of the N-type source region, and the width of the P-type conducting region is smaller than that of the N-type source region; the dielectric layer covers the surface of the device, an active region contact window is formed in the dielectric layer, the active region contact window exposes the middle region of the N-type source region, the middle region of the N-type source region exposed by the active region contact window is inverted to form a P-type contact region, the P-type contact region is connected with the P-type conductive region, and partial N-type source regions are reserved on two sides of the P-type contact region; and the conductive material is filled in the source region contact window to form a source region electrode.

Preferably, the ratio of the width of the source region contact window to the width of the N-type source region is between 0.4:1 and 1: 1.

Preferably, the P-type ion doping concentration of the P-type conduction region is greater than the N-type ion doping concentration of the N-type source region, wherein the P-type ion doping concentration of the P-type conduction region is not less than 5e17/cm³。

Preferably, the P-type ion doping concentration of the P-type contact region is greater than the N-type ion doping concentration of the N-type source region, wherein the N-type ion doping concentration of the N-type source region is 10¹⁷/cm³The order of magnitude, the P-type ion doping concentration of the P-type contact region is 10¹⁸/cm³An order of magnitude.

Preferably, the N-type source region extends in a long strip shape, and the source region contact windows are arranged at intervals along the extending direction of the N-type source region.

Preferably, an STI isolation region or a LOCOS isolation region is further formed in the N-type well region between the first gate unit and the second gate unit.

Preferably, the N-type drift region surrounds the STI isolation region or the LOCOS isolation region, and the doping concentration of the N-type drift region is 1e 16-1 e17/cm³。

Preferably, the P-type base comprises a P-type substrate, and the doping concentration of the P-type substrate is 1e 15-1 e16/cm³The doping concentration of the N-type well region is 1e 15-1 e16/cm³And the doping concentration of the N-type well region is greater than that of the P-type substrate, and the doping concentration of the P-type well region is 1e 17-1 e18/cm³。

Preferably, the P-type substrate comprises a P-type substrate and a P-type epitaxial layer formed on the P-type substrate, the N-type well region is formed in the P-type epitaxial layer, and the doping concentration of the P-type substrate is greater than that of the P-type epitaxial layer, wherein the doping concentration of the P-type epitaxial layer is 1e 15-1 e16/cm³The doping concentration of the P-type substrate is 1e 17-1 e18/cm³。

As described above, the semiconductor switch device and the method for manufacturing the same according to the present invention have the following advantageous effects:

1) according to the invention, after the grid structure is manufactured, the N-type source region is formed through comprehensive ion implantation without manufacturing a mask, so that the manufacturing of a mask is saved, after the surface protection dielectric layer is manufactured, the source region contact window is formed in the dielectric layer, and the P-type ion implantation is performed by taking the dielectric layer as the mask to form the P-type contact region.

2) According to the invention, the source region contact window is only exposed out of the middle region of the N-type source region, and after the middle region of the N-type source region exposed out of the source region contact window is inverted to form the P-type contact region, parts of the N-type source region are reserved on two sides of the P-type contact region, so that the on-resistance of the device can be effectively reduced, and the driving current of the device can be improved.

3) The P-type conductive region is formed at the lower part of the N-type source region, so that the resistance on a path of the P-type well region-N-type well region-P-type well region-N-type source region can be effectively reduced, the voltage on the path is reduced, and the generation of the lachtup effect (latch-up effect) of a semiconductor switching device caused by overhigh voltage of the path can be effectively avoided.

Drawings

Fig. 1a shows a schematic diagram of a typical lithium ion battery protection circuit.

Fig. 1b is a schematic diagram illustrating an arrangement of an N-type source region and a P-type contact region of a conventional semiconductor switch device.

Fig. 2 to 12 are schematic structural diagrams showing steps of a method for manufacturing a semiconductor switching device according to the present invention.

Fig. 13 is a schematic view showing the principle of preventing the latchup effect of the semiconductor switching device of the present invention.

Description of the element reference numerals

201P type substrate

202 side wall structure

203N type well region

204P-type well region

205 STI or LOCOS isolation regions

206 gate structure

2061 first gate unit

2062 second gate unit

207N type source region

208N type drift region

209 dielectric layer

210 source contact opening

211P type contact region

212 source region electrode

213P type conduction region

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

Please refer to fig. 2 to fig. 13. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of each component in actual implementation may be changed at will, and the layout of the components may be more complicated.

As shown in fig. 2 to 13, the present embodiment provides a method for manufacturing a semiconductor switching device, the method including the steps of:

as shown in fig. 2, step 1) is performed first, a P-type substrate 201 is provided, and then an STI (shallow trench isolation) region or a LOCOS (local silicon oxide isolation) region 205 is formed in the P-type substrate 201, where the STI or LOCOS isolation region 205 is located between a first gate unit 2061 and a second gate unit 2062 which are manufactured subsequently, and the STI or LOCOS isolation region 205 can effectively improve the voltage resistance of the device.

Specifically, the P-type base 201 comprises a P-type substrate, and the doping concentration of the P-type substrate is 1e 15-1 e16/cm³。

Of course, in other embodiments, the P-type substrate 201 may also include a P-type substrate and a P-type epitaxial layer formed on the P-type substrate, the N-well region 203 is formed in the P-type epitaxial layer, and the doping concentration of the P-type substrate is greater than that of the P-type epitaxial layer, wherein the doping concentration of the P-type epitaxial layer is 1e 15-1 e16/cm³The doping concentration of the P-type substrate is 1e 17-1 e18/cm³。

As shown in fig. 3, step 2) is then performed to form an N-well region 203 in the P-type substrate layer 201.

In particular, a maskless ion implantation method is adoptedAn N-type well region 203 is formed in the P-type substrate layer 201, and the doping concentration of the N-type well region 203 is 1e 15-1 e16/cm³And the doping concentration of the N-type well region 203 is greater than that of the P-type substrate 201.

As shown in fig. 4, step 3) is performed to form two spaced P-well regions 204 and an N-drift region 208 between the P-well regions in the N-well region 203.

Specifically, a mask is first formed according to a defined pattern of the P-type well region 204, and then two P-type well regions 204 arranged at intervals are formed in the N-type well region 203 by ion implantation, wherein the doping concentration of the P-type well region 204 is 1e 17-1 e18/cm³。

In this embodiment, the step 3) further includes a step of forming an N-type drift region 208 between the P-type well regions 204, the N-type drift region 208 surrounds the STI isolation region or the LOCOS isolation region 205, and a doping concentration of the N-type drift region 208 is 1e 16-1 e17/cm³. The N-type drift region 208 may serve as a drain region common to two transistors (MOSFETs) of the switching device to reduce on-resistance and increase on-current.

As shown in fig. 5, step 4) is then performed to fabricate a gate structure 206, where the gate structure 206 includes a first gate unit 2061 and a second gate unit 2062 spaced apart and crossing between the N-well region 203 and the P-well region 204.

As an example, a silicon dioxide layer is deposited as the gate dielectric layer 209, then polysilicon is deposited as the gate material, and then the polysilicon and the silicon dioxide layer are etched by photolithography-etching method to form the gate structure 206, where the gate structure 206 includes a first gate unit 2061 and a second gate unit 2062 spaced apart and crossing between the N-well region 203 and the P-well region 204.

As shown in fig. 6a to 6b, step 5) is performed, N-type ion implantation is performed using the gate structure 206 as a mask to form N-type source regions 207 in the P-type well region 204, the N-type source regions 207 are respectively located at outer sides of the first gate unit 2061 and the second gate unit 2062, meanwhile, an N-type drift region 208 is formed between the first gate unit 2061 and the second gate unit 2062 during the N-type ion implantation, and the N-type drift region 208 surrounds the STI isolation region or the LOCOS isolation region 205.

Specifically, without additional mask fabrication, N-type ion implantation is performed with the gate structure 206 as a mask to form an N-type source region 207 in the P-type well region 204. After the gate structure 206 is manufactured, the N-type source region 207 is formed by the overall ion implantation without manufacturing a mask, so that the manufacturing of the mask is saved.

As shown in fig. 7 to 8, step 6) is then performed to fabricate a sidewall structure 202 on a side surface of the gate structure 206, and then P-type ion implantation is performed by using the gate structure 206 and the sidewall structure 202 as masks to form a P-type conductive region 213 on a lower portion of the N-type source region 207, where a width of the P-type conductive region 213 is smaller than a width of the N-type source region. By manufacturing the side wall structure 202, the P-type conductive region 213 can be formed by directly performing ion implantation without additionally increasing a mask, and the width of the P-type conductive region 213 is smaller than that of the N-type source region, so that the process cost can be effectively reduced.

As an example, the dosage of the P-type ion implantation for forming the P-type conductive region 213 in step 6) is greater than the dosage of the N-type ion implantation for forming the N-type source region 207 in step 5), wherein the dosage of the P-type ion implantation for forming the P-type conductive region 213 in step 6) is not less than 5e15/cm². The P-type conductive region 213 is formed under the N-type source region 207, so that the resistance Rb on the PNPN path (shown by the dotted arrow in fig. 13) of the P-type well region-N-type well region-P-type well region-N-type source region can be effectively reduced, the voltage on the path can be reduced to be less than 0.7V (i.e., less than the on-state voltage of a silicon-based PN junction), the generation of leakage between the N-type source region and the P-type well region under the control of the voltage can be avoided, and the generation of the latch-up effect (latch-up effect) of the semiconductor switching device due to the overhigh voltage of the path can be effectively avoided.

As shown in fig. 9 to 11, fig. 10a is a schematic cross-sectional view taken along line a-a' in fig. 10b, and then step 7) is performed to form a dielectric layer 209 on the device surface, form a source contact window 210 in the dielectric layer 209, expose a middle region of the N-type source region 207 through the source contact window 210, perform P-type ion implantation based on the source contact window 210 with the dielectric layer 209 as a mask, so that the exposed middle region of the N-type source region 207 is inverted to form a P-type contact region 211, the P-type contact region 211 is connected to the P-type conductive region 213 (to further reduce resistance), and portions of the N-type source region 207 remain on both sides of the P-type contact region 211.

Specifically, a silicon dioxide layer is formed on the surface of the device by chemical vapor deposition as the dielectric layer 209, then, a mask pattern is made and the dielectric layer 209 is etched, a source region contact window 210 is formed in the dielectric layer 209, the source region contact opening 210 exposes a middle region of the N-type source region 207, a P-type ion implantation is performed based on the source region contact opening 210, the exposed middle region of the N-type source region 207 is inverted to form a P-type contact region 211, a portion of the N-type source region 207 remains on both sides of the P-type contact region 211, wherein, the dosage of the P-type ion implantation for forming the P-type contact region 211 in the step 7) is larger than that of the N-type ion implantation for forming the N-type source region 207 in the step 5), for example, the dosage of the N-type ion implantation for forming the N-type source region 207 in step 5) is 10.¹⁵/cm²Order of magnitude, the dose of the P-type ion implantation forming the P-type contact regions 211 in step 6) is 10¹⁶/cm²An order of magnitude. In the invention, after the surface protection dielectric layer 209 is manufactured, the source region contact window 210 is formed in the dielectric layer 209, and the dielectric layer 209 is taken as a mask to carry out P-type ion implantation to form the P-type contact region 211

The N-type source region 207 extends in a long strip shape, as shown in fig. 6b, and the source contact windows 210 are arranged at intervals along the extending direction of the N-type source region 207, as shown in fig. 10 b.

The ratio of the width of the source contact window 210 to the width of the N-type source region 207 is between 0.4:1 and 1:1, and preferably, the ratio of the width of the source contact window 210 to the width of the N-type source region 207 is between 0.4:1 and 0.8:1, so that after the P-type contact region 211 is formed by P-ion implantation, the remaining width of the N-type source region 207 can reach 20% to 60% of the entire width of the original N-type source region 207. In the invention, after the middle region of the N-type source region 207 exposed by the source region contact window 210 is inverted to form the P-type contact region 211, parts of the N-type source region 207 are reserved on both sides of the P-type contact region 211, so that the on-resistance of the device can be effectively reduced, and the driving current of the device can be improved.

As shown in fig. 12, step 8) is then performed to fill the source region contact window 210 with a conductive material to form a source region electrode 212.

For example, after the source region contact window 210 is filled with a conductive material, annealing is performed to make the conductive material react with the P-type contact region 211 and the N-type source region 207 to form a metal silicide, so that the source region electrode 212 is simultaneously in contact with the P-type contact region 211 and the N-type source region 207 to reduce the contact resistance.

As shown in fig. 12, the present embodiment also provides a semiconductor switching device including: a P-type substrate 201; an N-well 203 formed in the P-type substrate layer 201; p-type well regions 204 formed in the N-type well region 203 at intervals; a gate structure 206, wherein the gate structure 206 includes a first gate unit 2061 and a second gate unit 2062 spaced apart and crossing between the N-well region 203 and the P-well region 204; an N-type source region 207 formed in the P-type well region 204 outside the first gate unit 2061 and the second gate unit 2062; a sidewall structure 202 located on a side surface of the gate structure 206; a P-type conductive region 213 formed at a lower portion of the N-type source region 207, wherein a width of the P-type conductive region 213 is smaller than a width of the N-type source region 207; a dielectric layer 209 covering the device surface, wherein an active region contact window 210 is formed in the dielectric layer 209, the active region contact window 210 exposes the middle region of the N-type source region 207, the middle region of the N-type source region 207 exposed by the active region contact window 210 is inverted to form a P-type contact region 211, the P-type contact region 211 is connected with the P-type conducting region 213, and a part of the N-type source region 207 is reserved on both sides of the P-type contact region 211; and a conductive material filled in the source contact window 210 to form a source region electrode 212.

For example, the ratio of the width of the source contact window 210 to the width of the N-type source region 207 is between 0.4:1 and 1:1, and preferably, the ratio of the width of the source contact window 210 to the width of the N-type source region 207 is between 0.4:1 and 0.8:1, so that after the P-type contact region 211 is formed by P-ion implantation, the remaining width of the N-type source region 207 may reach 20% to 60% of the entire width of the original N-type source region 207. In the invention, after the middle region of the N-type source region 207 exposed by the source region contact window 210 is inverted to form the P-type contact region 211, parts of the N-type source region 207 are reserved on both sides of the P-type contact region 211, so that the on-resistance of the device can be effectively reduced, and the driving current of the device can be improved.

As an example, the P-type ion doping concentration of the P-type conduction region 213 is greater than the N-type ion doping concentration of the N-type source region 207, wherein the P-type ion doping concentration of the P-type conduction region 213 is not less than 5e17/cm³。

As an example, the P-type ion doping concentration of the P-type contact region 211 is greater than the N-type ion doping concentration of the N-type source region 207.

As an example, the N-type source region 207 has an N-type ion doping concentration of 10¹⁷/cm³In order of magnitude, the P-type ion doping concentration of the P-type contact region 211 is 10¹⁸/cm³An order of magnitude.

As an example, the N-type source region 207 extends in a long stripe shape, and the source region contact windows 210 are arranged at intervals along the extending direction of the N-type source region 207.

As an example, an STI isolation region or a LOCOS isolation region 205 is further formed in the N-type well region 203 between the first gate unit 2061 and the second gate unit 2062.

As an example, an N-type drift region 208 is further formed in the N-type well region 203 between the first gate unit 2061 and the second gate unit 2062, the N-type drift region 208 surrounds the STI isolation region or the LOCOS isolation region 205, and the doping concentration of the N-type drift region 208 is 1e 16-1 e17/cm³。

As an example, the P-type substrate 201 may be a P-type substrate with a doping concentration of 1e 15-1 e16/cm³The doping concentration of the N-type well region 203 is 1e 15-1 e16/cm³And the doping concentration of the N-type well region 203 is greater than that of the P-type substrate 201, and the doping concentration of the P-type well region 204 is 1e 17-1 e18/cm³。

Of course, in other embodiments, the P-type substrate 201 may also include a P-type substrate and a P-type epitaxial layer formed on the P-type substrate, the N-well 203 is formed in the P-type epitaxial layer, and the doping concentration of the P-type substrate is greater than that of the P-type epitaxial layer, wherein the doping concentration of the P-type epitaxial layer is 1e 15-1 e16/cm³The doping concentration of the P-type substrate is 1e 17-1 e18/cm³。

As described above, the semiconductor switch device and the method for manufacturing the same according to the present invention have the following advantageous effects:

1) according to the invention, after the grid structure is manufactured, the N-type source region is formed through comprehensive ion implantation without manufacturing a mask, so that the manufacturing of a mask is saved, after the surface protection dielectric layer is manufactured, the source region contact window is formed in the dielectric layer, and the P-type ion implantation is performed by taking the dielectric layer as the mask to form the P-type contact region.

2) According to the invention, the source region contact window is only exposed out of the middle region of the N-type source region, and after the middle region of the N-type source region exposed out of the source region contact window is inverted to form the P-type contact region, parts of the N-type source region are reserved on two sides of the P-type contact region, so that the on-resistance of the device can be effectively reduced, and the driving current of the device can be improved.

3) The P-type conductive region is formed at the lower part of the N-type source region, so that the resistance on a path of the P-type well region-N-type well region-P-type well region-N-type source region can be effectively reduced, the voltage on the path is reduced, and the generation of the lachtup effect (latch-up effect) of a semiconductor switching device caused by overhigh voltage of the path can be effectively avoided.

Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which may be accomplished by those skilled in the art without departing from the spirit and scope of the present invention as set forth in the appended claims.