JP4951857B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a method for manufacturing a semiconductor device in which a bipolar transistor and a Zener diode are formed on the same semiconductor substrate.

  A semiconductor device in which a bipolar transistor and a Zener diode are formed on the same semiconductor substrate and a method for manufacturing the same are disclosed in, for example, Japanese Patent Application Laid-Open No. 11-233641 (Patent Document 1).

  In a semiconductor device in which the bipolar transistor and the zener diode are formed on the same semiconductor substrate, the p-conductivity type and n-conductivity type diffusion regions constituting the bipolar transistor and the p-conductivity type and n-conductivity type constituting the zener diode are usually used. Each of the diffusion regions is formed using the same diffusion process. Thereby, the manufacturing process of the semiconductor device can be reduced and the cost can be reduced.

  An example of the semiconductor device and a method for manufacturing the same will be described with reference to FIGS.

  FIG. 5A is a schematic cross-sectional view of the semiconductor device 90, which is a semiconductor device in which a bipolar transistor T1 and a Zener diode D1 are formed on the same semiconductor substrate 1. FIG.

  The bipolar transistor T1 of the semiconductor device 90 is an NPN type bipolar transistor, and includes an n + diffusion region 1e as an emitter, a p + diffusion region 1b as a base, and an n + diffusion region 1c as a collector. In addition, the code | symbol 1a in a figure is the isolation using PN junction isolation | separation. The diffusion regions 1e, 1b, and 1c of the bipolar transistor T1 are connected to electrodes 3Te, 3Tb, and 3Tc made of aluminum (Al) through an interlayer insulating film 2, and the surface is a protective film 4 made of a silicon nitride film or the like. Protected.

  The Zener diode D1 of the semiconductor device 90 is formed using the structure of the diffusion regions 1e, 1b, 1c of the bipolar transistor T1 as it is. The cathode electrode 3Dc of the Zener diode D1 corresponds to the emitter electrode 3Te in the bipolar transistor T1, and the anode electrode 3Da of the Zener diode D1 corresponds to an electrode connecting the base electrode 3Tb and the collector electrode 3Tc in the bipolar transistor T1.

  FIG. 5B is a process flow diagram illustrating an outline of a conventional method for manufacturing the semiconductor device 90.

  Using the semiconductor substrate 1 on which the buried n + and the buried p + are formed, first, in step K1, an isolation 1a is formed.

  As described above, since the diffusion region structure of the bipolar transistor T1 and the diffusion region structure of the Zener diode D1 in the semiconductor device 90 are the same, the diffusion regions in both are simultaneously used as follows using the same diffusion process as follows. It is formed.

  In step K2, the p + diffusion region 1b of the bipolar transistor T1 and the Zener diode D1 is formed. In the formation of the p + diffusion region 1b, for example, boron (B) is ion-implanted and then heat-treated in a nitrogen atmosphere at 1150 ° C. or higher for about 100 minutes.

  Next, in step K3, n + diffusion regions 1e and 1c of the bipolar transistor T1 and the Zener diode D1 are formed. In the formation of the n + diffusion regions 1e and 1c, for example, after phosphorus oxychloride is deposited, drive-in is performed for about 20 minutes while pyrooxidizing at 1000 ° C. or higher.

  Next, in step K4, contacts of the interlayer insulating film 2 and Al electrodes 3Te, 3Tb, 3Tc, 3Dc, 3Da are formed. In forming the Al electrodes 3Te, 3Tb, 3Tc, 3Dc, 3Da, Al is sintered at 450 ° C. in order to make contact with the diffusion regions 1e, 1b, 1c.

  Next, in step K5, the protective film 4 is formed. In the formation of the protective film 4, annealing at 450 ° C. is performed for the purpose of recovery of plasma damage and the like.

Thus, the semiconductor device 90 shown in FIG. 5A is manufactured.
Japanese Patent Laid-Open No. 11-233641

  In a semiconductor device (bipolar IC circuit) in which a bipolar transistor T1 and a Zener diode D1 are formed on the same semiconductor substrate 1 as in the semiconductor device 90 shown in FIG. 5A, the Zener diode D1 has, for example, a reference voltage Used to set the reference voltage of the circuit. The Zener diode D1 used in such a reference voltage circuit is required to have a highly accurate Zener voltage Vz. On the other hand, for the purpose of reducing the manufacturing process and reducing the cost, the Zener diode D1 is formed using the diffusion region 1e, 1b, 1c structure of the bipolar transistor T1 as it is.

  The adjustment of the Zener voltage Vz of the Zener diode D1 and the current amplification factor hFE which is the main characteristic of the bipolar transistor T1 in the semiconductor device 90 is performed by adjusting the processing conditions of the two diffusion region forming steps K2 and K3 shown in FIG. This is done by controlling the concentration profile of the diffusion region. However, in an in-vehicle semiconductor device or the like, the two diffusion region forming steps K2 and K3 are usually performed at a high temperature of 1000 ° C. or higher, and when the current amplification factor hFE of the bipolar transistor T1 is adjusted, the Zener voltage of the Zener diode D1 also varies. The reverse is also true. For this reason, it is difficult to independently control only the Zener voltage Vz requiring high accuracy to an arbitrary value.

  Accordingly, an object of the present invention is a method of manufacturing a semiconductor device in which a bipolar transistor and a Zener diode are formed on the same semiconductor substrate, and the Zener voltage of the Zener diode is not affected without affecting the current amplification factor hFE of the bipolar transistor. An object of the present invention is to provide a low-cost manufacturing method capable of adjusting only Vz with high accuracy.

The invention according to claim 1 is a method for manufacturing a semiconductor device in which a bipolar transistor and a Zener diode are formed on the same semiconductor substrate, wherein the p-conductivity type diffusion region constituting the bipolar transistor and the Zener diode are formed. diffusion region of p conductivity type constituting, simultaneously formed by using the same spreading step performed at 1000 ° C. or more, of n conductivity type constituting the said Zener diode and the diffusion region of n conductivity type constituting the bipolar transistor diffusion regions, and forming at the same time using the same spreading process performed at 1 000 ° C. or more, the two semiconductor substrates after the diffusion step is completed, in a nitrogen atmosphere, 550 ° C. or higher, a heat treatment in a temperature range of 800 ° C. or less It is characterized by that.

In the manufacturing method of the semiconductor device, the p-conduction type diffusion region constituting the bipolar transistor and the p-conduction type diffusion region constituting the Zener diode are simultaneously formed by using the same diffusion step performed at 1000 ° C. or more. the n-type conductivity diffusion region forming the n conductivity type diffusion region and a Zener diode for a transistor, formed at the same time using the same spreading process performed at 1 000 ° C. or more.
As described above, the semiconductor device manufacturing method includes a p-conduction type diffusion region constituting a bipolar transistor, a p-conduction type diffusion region constituting a Zener diode, and an n-conduction type diffusion region constituting a bipolar transistor and a Zener. the n conductivity type diffusion region constituting a diode, a manufacturing method which aimed at the cost of forming at the same time using the same spreading process performed at each 1000 ° C. or higher, the low-temperature heat treatment in the two diffusion process after completion of the It has become a low-cost manufacturing just by adding.
In the manufacture of an in-vehicle semiconductor device, the diffusion process is generally performed at a high temperature of 1000 ° C. or higher. Therefore, the method for manufacturing a semiconductor device can also be applied to the manufacture of an in-vehicle semiconductor device.
On the other hand, when the current amplification factor hFE of the bipolar transistor is adjusted in the diffusion step performed at 1000 ° C. or higher, the Zener voltage Vz of the Zener diode also varies, and vice versa. Therefore, it is difficult to adjust both to arbitrary values only by adjusting the processing conditions of the diffusion step.
For this reason, in the manufacturing method of the semiconductor device, heat treatment is performed in a temperature range of 550 ° C. or higher and 800 ° C. or lower after completion of the diffusion step. The heat treatment is at a relatively low temperature compared to the diffusion step performed at 1000 ° C. or higher, and the concentration profiles of the p-conductivity type and n-conductivity type diffusion regions formed in the diffusion step hardly change. For this reason, the base width that contributes most to the current amplification factor hFE of the bipolar transistor is hardly changed by the heat treatment performed after the diffusion step. On the other hand, the Zener voltage Vz of the Zener diode is also greatly contributed by the interface state of the PN junction portion that is not directly related to the concentration profile. For this reason, the Zener voltage Vz of the Zener diode D2 can be adjusted by a relatively low temperature heat treatment performed after the end of the diffusion process. The Zener voltage Vz is adjusted by changing the heat treatment time.
As described above, according to the semiconductor device manufacturing method, the current amplification factor hFE of the bipolar transistor is set to a predetermined value in the diffusion region forming step, and the bipolar transistor is processed in the low-temperature heat treatment step after the diffusion step. Only the zener voltage Vz of the zener diode can be adjusted to an arbitrary value with high accuracy without affecting the current amplification factor hFE.

  As described above, the method for manufacturing a semiconductor device is a method for manufacturing a semiconductor device in which a bipolar transistor and a Zener diode are formed on the same semiconductor substrate, and affects the current amplification factor hFE of the bipolar transistor. In other words, the manufacturing method can adjust only the Zener voltage Vz of the Zener diode with high accuracy.

In the method of manufacturing the semiconductor device, as described in claim 2, for example, the formation of the p conductivity type diffusion region is a drive-in of boron (B) by heat treatment at 1150 ° C. or more, and the n conductivity type The formation of the diffusion region is a drive-in of phosphorus (P) by heat treatment at 1000 ° C. or higher.
Further, as described in claim 3 , the temperature range of the heat treatment after the end of the diffusion step is more preferably 600 ° C. or more and 700 ° C. or less.
Further, in the method for manufacturing the semiconductor device, for example, as described in claim 4, the time for the heat treatment after the end of the diffusion step is within 30 minutes.

  Thus, the adjustment range of the Zener voltage Vz of the Zener diode can be maximized within a range that does not affect the current amplification factor hFE of the bipolar transistor.

  6. The method of manufacturing a semiconductor device according to claim 5, wherein the bipolar transistor is an NPN bipolar transistor, the Zener diode has the same diffusion region structure as the bipolar transistor, and the Zener diode. The cathode electrode of the bipolar transistor corresponds to the emitter electrode of the bipolar transistor, and the anode electrode of the Zener diode corresponds to the electrode connecting the base electrode and the collector electrode of the bipolar transistor. The present invention can also be applied to the manufacture of inexpensive semiconductor devices.

  According to a sixth aspect of the present invention, the method for manufacturing a semiconductor device is suitable when the Zener diode is a Zener diode used for setting a reference voltage of a reference voltage circuit.

  A Zener diode used for setting the reference voltage of the reference voltage circuit is required to have a highly accurate Zener voltage Vz. Therefore, the method of manufacturing a semiconductor device capable of adjusting the Zener voltage Vz to an arbitrary value with high accuracy is a method of manufacturing a semiconductor device in which a Zener diode used for setting a reference voltage of a reference voltage circuit is formed together with a bipolar transistor. It is suitable for.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1A is a schematic cross-sectional view of a semiconductor device 100 manufactured using the manufacturing method of the present invention, and FIG. 1B shows a method of manufacturing the semiconductor device 100 of FIG. It is a process flow figure showing an outline. In the semiconductor device 100 shown in FIG. 1A, the same parts as those in the semiconductor device 90 shown in FIG. Also, in the manufacturing process of the semiconductor device 100 shown in FIG. 1B, the same reference numerals are given to the same processes as the manufacturing process of the semiconductor device 90 shown in FIG.

  A semiconductor device 100 shown in FIG. 1A includes a bipolar transistor T2 and a Zener diode D2 formed on the same semiconductor substrate 10, and is structurally similar to the semiconductor device 90 shown in FIG. 5A. is there.

  That is, the bipolar transistor T2 in the semiconductor device 100 of FIG. 1A is an NPN-type bipolar transistor and includes an n + diffusion region 10e as an emitter, a p + diffusion region 10b as a base, and an n + diffusion region 10c as a collector. ing. In addition, the code | symbol 10a in a figure is the isolation using PN junction isolation | separation. Electrodes 3Te, 3Tb, 3Tc made of aluminum (Al) are connected to the diffusion regions 10e, 10b, 10c of the bipolar transistor T2 via the interlayer insulating film 2, and the surface is a protective film 4 made of a silicon nitride film or the like. Protected.

  Further, the Zener diode D2 of the semiconductor device 100 is formed using the structure of the diffusion regions 10e, 10b, and 10c of the bipolar transistor T2 as they are. The cathode electrode 3Dc of the Zener diode D2 corresponds to the emitter electrode 3Te in the bipolar transistor T2, and the anode electrode 3Da of the Zener diode D2 corresponds to the electrode connecting the base electrode 3Tb and the collector electrode 3Tc in the bipolar transistor T2.

  On the other hand, in the process flow diagram of the semiconductor device 100 shown in FIG. 1B, as can be seen from the process flow diagram of the semiconductor device 90 shown in FIG. The heat treatment step L1 is added.

  That is, the semiconductor device 100 of FIG. 1A is manufactured as follows.

  First, in step K1, an isolation 10a for element isolation is formed using the semiconductor substrate 10 in which the buried n + and the buried p + are formed. In the formation of the isolation 10a, after forming an oxide film, it is processed into a mask pattern through photolithography and etching processes. For example, after depositing a boron (B) diffusion source, heat treatment is performed at 1150 ° C. or higher and drive-in is performed. .

  As described above, since the diffusion region structure of the bipolar transistor T2 and the diffusion region structure of the Zener diode D2 in the semiconductor device 100 are the same, each diffusion region in both uses the same diffusion step as shown below. Are formed at the same time.

  In step K2, the p + diffusion region 10b of the bipolar transistor T2 and the Zener diode D2 is formed. In the formation of the p + diffusion region 10b, after forming an oxide film, it is processed into a mask pattern through photolithography and etching processes. For example, after boron (B) is ion-implanted, it is about 100 at 1150 ° C. or higher in a nitrogen atmosphere. Heat in for a minute and drive in.

  Next, in step K3, n + diffusion regions 10e and 10c of the bipolar transistor T2 and the Zener diode D2 are formed. In the formation of the n + diffusion regions 10e and 10c, after forming an oxide film, it is processed into a mask pattern through photolithography and etching processes. For example, phosphorus oxychloride is deposited or phosphorus (P) ions are implanted, and then 1000 ° C. Drive in for about 20 minutes while pyro oxidizing as above.

  Next, in step L1, the semiconductor substrate 10 after completion of the diffusion step in which the isolation 10a and the diffusion regions 10e, 10b, and 10c are formed is heat-treated in a nitrogen atmosphere at a temperature range of 500 ° C. or higher and 900 ° C. or lower.

  Next, in step K4, contacts of the interlayer insulating film 2 and Al electrodes 3Te, 3Tb, 3Tc, 3Dc, 3Da are formed. In the formation of the Al electrodes 3Te, 3Tb, 3Tc, 3Dc, 3Da, after forming an Al film, it is processed into a predetermined electrode wiring pattern through photolithography and etching processes, and contacts with the diffusion regions 10e, 10b, 10c are made. Therefore, Al sintering is performed at 450 ° C.

  Next, in step K5, the protective film 4 is formed. In the formation of the protective film 4, a silicon nitride film or the like is deposited by, for example, plasma CVD, and then annealed at 450 ° C. for the purpose of plasma damage recovery or the like.

  Thus, the semiconductor device 100 shown in FIG. 1A is manufactured.

  In the process flow diagram of the semiconductor device 100 of FIG. 1B described above, unlike the process flow diagram of the semiconductor device 90 of FIG. 5B, a heat treatment step L1 of 500 to 900 ° C. is added. Accordingly, the diffusion regions 10e, 10b, and 10c in the semiconductor device 100 of FIG. 1A are different from the diffusion regions 1e, 1b, and 1c in the semiconductor device 90 of FIG. The diffusion region is subjected to the heat treatment in step L1.

  The manufacturing method of the semiconductor device 100 shown in FIG. 1B is a manufacturing method of a semiconductor device in which the bipolar transistor T2 and the Zener diode D2 are formed on the same semiconductor substrate 10, and includes the p that constitutes the bipolar transistor T2. Conduction type and n conductivity type diffusion regions and p conductivity type and n conductivity type diffusion regions constituting the Zener diode D2 are formed using the same diffusion steps K2 and K3, respectively, and after the diffusion steps K2 and K3 are completed. The semiconductor substrate 10 is characterized in that it is heat-treated in a temperature range of 500 ° C. or more and 900 ° C. or less in a nitrogen atmosphere in the heat treatment step L1.

  The heat treatment performed in the heat treatment step L1 is a relatively low temperature, and the concentration profiles of the p conductivity type and n conductivity type diffusion regions 10e, 10b, and 10c formed in the diffusion steps K2 and K3 hardly change. Therefore, the base width w that contributes most to the current amplification factor hFE of the bipolar transistor T2 shown in FIG. 1A is hardly changed by the heat treatment in the heat treatment step L1. On the other hand, the Zener voltage Vz of the Zener diode D2 is greatly contributed by the interface state of the PN junction portion indicated by the thick dotted line b in the figure which is not directly related to the concentration profile. For this reason, the Zener voltage Vz of the Zener diode D2 can be adjusted by a relatively low temperature heat treatment performed in the heat treatment step L1.

  An example of the heat treatment effect is shown in FIGS. FIG. 2A shows the result of examining the Zener voltage Vz of the Zener diode D2 with respect to the heat treatment time by heat treatment at 600 ° C. in a nitrogen atmosphere. FIG. 2B shows the result of examining the current amplification factor hFE of the bipolar transistor T2 with respect to the heat treatment time by heat treatment at 600 ° C. in the same nitrogen atmosphere. With the heat treatment at 600 ° C. for 30 minutes, the Zener voltage Vz of the Zener diode D2 increases from 7.45V to 7.72V, and the current amplification factor hFE of the bipolar transistor T2 increases from 160 to 180.

  FIG. 3 shows the change rate of the Zener voltage Vz and the current amplification factor hFE in the heat treatment step L1 obtained from FIGS. 2A and 2B with respect to the heat treatment time in the diffusion steps K2 and K3 used for the conventional adjustment. It is the figure shown by comparing with the change rate.

  In the conventional heat treatment in the diffusion steps K2 and K3 of FIG. 3, the rate of change of the current amplification factor hFE with respect to the heat treatment time is also a large value as well as the rate of change of the Zener voltage Vz with respect to the heat treatment time. For this reason, it is difficult to independently control only the Zener voltage Vz requiring high accuracy to an arbitrary value.

  On the other hand, in the heat treatment at 600 ° C. in the heat treatment step L1 of FIG. 3, the rate of change of the current amplification factor hFE with respect to the heat treatment time is a very small value. Therefore, the heat treatment at 600 ° C. in the heat treatment step L1 of FIG. 3 adjusts only the Zener voltage Vz of the Zener diode D2 with high accuracy without affecting the current amplification factor hFE of the bipolar transistor T2 shown in FIG. can do. The Zener voltage Vz is adjusted by changing the heat treatment time as shown in FIG.

  As can be seen from the above description, the semiconductor device manufacturing method of the present invention in which only the zener voltage Vz of the zener diode D2 is adjusted by adding the heat treatment step L1 is particularly suitable for the diffusion steps K2, K3 shown in FIG. Is suitable when it is carried out at 1000 ° C. or higher.

  In the manufacture of an in-vehicle semiconductor device, the diffusion steps K2 and K3 shown in FIG. 1B are generally performed at a high temperature of 1000 ° C. or higher. As shown in FIG. 3, when the current amplification factor hFE of the bipolar transistor T1 shown in FIG. 5A is adjusted in the diffusion steps K2 and K3, the Zener voltage Vz of the Zener diode D1 also fluctuates, and vice versa. is there. Therefore, it is difficult to adjust both to arbitrary values only by adjusting the processing conditions of the diffusion steps K2 and K3.

  On the other hand, according to the semiconductor device manufacturing method, the current amplification factor hFE of the bipolar transistor T2 is set to a predetermined value in the diffusion processes K2 and K3, and the bipolar heat treatment process L1 after the diffusion processes K2 and K3 is completed. Only the Zener voltage Vz of the Zener diode D2 can be adjusted to an arbitrary value with high accuracy without affecting the current amplification factor hFE of the transistor T2. In this way, the Zener voltage Vz of the Zener diode D2 can be adjusted within a certain range while minimizing the characteristic fluctuation of the current amplification factor hFE of the bipolar transistor T2, and the required accuracy of the Zener voltage Vz is high. As a result, the yield is improved. Furthermore, it is effective for energy saving by improving the yield.

  FIG. 4 shows the results of examining the relationship between the heat treatment temperature and the rate of change of the Zener voltage Vz and the current amplification factor hFE with respect to the heat treatment time in the heat treatment step L1.

  From the result of FIG. 4, when the heat treatment temperature is lower than 500 ° C., the change rate of the Zener voltage Vz with respect to the heat treatment time is too small to adjust the Zener voltage Vz. On the other hand, when the heat treatment temperature is higher than 900 ° C., the rate of change of the current amplification factor hFE with respect to the heat treatment time increases rapidly. For this reason, in the heat treatment step L1 shown in FIG. 1B, it is necessary to heat treat the semiconductor substrate 10 after the diffusion steps K2 and K3 in a temperature range of 500 ° C. to 900 ° C. in a nitrogen atmosphere.

  From the results of FIG. 4, the temperature range of the heat treatment is more preferably 550 ° C. or more and 800 ° C. or less, and further preferably 600 ° C. or more and 700 ° C. or less. Thus, the adjustment range of the Zener voltage Vz of the Zener diode D2 can be maximized within a range that does not affect the current amplification factor hFE of the bipolar transistor T2.

  In the semiconductor device manufacturing method, the p conductivity type and n conductivity type diffusion regions constituting the bipolar transistor T2 shown in FIG. 1A and the p conductivity type and n conductivity type diffusion regions constituting the Zener diode D2 are respectively provided. 1B is a manufacturing method aiming at cost reduction formed by using the same diffusion processes K2 and K3 shown in FIG. 1B, and a low-cost manufacturing only by adding a low-temperature heat treatment process L1 after the completion of the diffusion processes K2 and K3. It is.

  In particular, in the semiconductor device 100 shown in FIG. 1A, the bipolar transistor T2 is an NPN-type bipolar transistor, the Zener diode D2 has the same diffusion region structure as the bipolar transistor T2, and the cathode electrode of the Zener diode D2 3Dc corresponds to the emitter electrode 3Te in the bipolar transistor T2, and the anode electrode 3Da of the Zener diode D2 corresponds to an electrode obtained by connecting the base electrode 3Tb and the collector electrode 3Tc in the bipolar transistor T2. As described above, the semiconductor device 100 shown in FIG. 1A is an inexpensive semiconductor device in which the diffusion region structure is unified to reduce the cost. The manufacturing method of the semiconductor device of the present invention in which only the Zener voltage Vz of the Zener diode D2 is adjusted by adding the heat treatment step L1 is the manufacturing method of an inexpensive semiconductor device in which the diffusion region structure of the bipolar transistor and the Zener diode is unified. It can also be applied to.

  In addition, the semiconductor device manufacturing method is suitable when the Zener diode D2 formed in the semiconductor device 100 of FIG. 1B is used for setting the reference voltage of the reference voltage circuit.

  A Zener diode used for setting the reference voltage of the reference voltage circuit is required to have a highly accurate Zener voltage Vz. Therefore, the semiconductor device manufacturing method capable of adjusting the Zener voltage Vz to an arbitrary value with high accuracy is a semiconductor device in which the Zener diode D2 used for setting the reference voltage of the reference voltage circuit is formed together with the bipolar transistor T2. It is suitable for manufacturing.

  As described above, the semiconductor device manufacturing method in which the bipolar transistor T2 and the Zener diode D2 are formed on the same semiconductor substrate 10 does not affect the current amplification factor hFE of the bipolar transistor T2, and does not affect the Zener diode D2. This is an energy-saving and low-cost manufacturing method in which only the zener voltage Vz can be adjusted with high accuracy.

(A) is typical sectional drawing of the semiconductor device 100 manufactured using the manufacturing method of this invention, (b) is a process flowchart which shows the outline of the manufacturing method of the semiconductor device 100 of (a). It is. (A), (b) is a figure which shows an example of the heat processing effect. The change rate with respect to the heat treatment time of the zener voltage Vz and the current amplification factor hFE in the heat treatment step L1 obtained from FIGS. 2 (a) and 2 (b) is the change rate in the diffusion steps K2 and K3 used for the conventional adjustment. It is the figure shown in comparison. It is the result of investigating the relationship between the change rate of the zener voltage Vz and the current amplification factor hFE with respect to the heat treatment time and the heat treatment temperature in the heat treatment step L1. (A) is typical sectional drawing of the semiconductor device 90, (b) is a process flow figure which shows the outline of the conventional manufacturing method of the semiconductor device 90 of (a).

Explanation of symbols

90,100 Semiconductor device T1, T2 Bipolar transistor D1, D2 Zener diode 1,10 Semiconductor substrate 1a, 10a Isolation 1e, 1c, 10e, 10c (n +) Diffusion region 1b, 10b (p +) Diffusion region 2 Interlayer insulating film 3Te , 3Tb, 3Tc, 3Dc, 3Da Electrode 4 Protective film K2, K3 Diffusion process L1 (Heat treatment in a temperature range of 500 ° C. to 900 ° C.) Heat treatment step

Claims (6)

A method of manufacturing a semiconductor device in which a bipolar transistor and a Zener diode are formed on the same semiconductor substrate,
Forming simultaneously the p-conduction type diffusion region constituting the bipolar transistor and the p-conduction type diffusion region constituting the zener diode using the same diffusion step performed at 1000 ° C. or higher;
The n-type conductivity diffusion region forming the n conductivity type diffusion region and the Zener diode configuring the bipolar transistor, and forming at the same time using the same spreading process performed at 1 000 ° C. or more,
A method of manufacturing a semiconductor device, comprising: heat-treating a semiconductor substrate after completion of the two diffusion steps in a nitrogen atmosphere at a temperature range of 550 ° C. to 800 ° C. The formation of the p conductivity type diffusion region is a drive-in of boron (B) by heat treatment at 1150 ° C. or higher,
2. The method of manufacturing a semiconductor device according to claim 1, wherein the formation of the n conductivity type diffusion region is a drive-in of phosphorus (P) by heat treatment at 1000 [deg.] C. or more.   3. The method of manufacturing a semiconductor device according to claim 1, wherein a temperature range of the heat treatment after the diffusion step is 600 ° C. or more and 700 ° C. or less.   4. The method of manufacturing a semiconductor device according to claim 1, wherein the heat treatment time after the end of the diffusion process is within 30 minutes. 5. The bipolar transistor is an NPN-type bipolar transistor;
The Zener diode has the same diffusion region structure as the bipolar transistor, the cathode electrode of the Zener diode corresponds to the emitter electrode in the bipolar transistor, and the anode electrode of the Zener diode is connected to the base electrode in the bipolar transistor. the method of manufacturing a semiconductor device according to any one of claims 1 to 4, characterized in that corresponding to the electrode connected to the collector electrode.   The method of manufacturing a semiconductor device according to claim 1, wherein the Zener diode is a Zener diode used for setting a reference voltage of a reference voltage circuit.

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