JPH02253654A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To avoid damage of the surface of a substrate and to prevent deterioration of characteristics of a bipolar transistor and decrease in yield by previously forming a field oxide film on base, emitter forming regions of the transistor. CONSTITUTION:The sidewall 16 of a gate electrode 13 of a MOSFET is formed in a state that the base, emitter regions of a bipolar transistor are covered with a field oxide film 11. Then, the films 11 of base, emitter forming regions 9 are selectively removed to form a base diffused layer 20 of the transistor. Thus, since the surface of a semiconductor substrate 1 is not damaged at the time of formation of the sidewall 16, the deterioration of characteristic of the transistor and the decrease in yield can be prevented.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a semiconductor device in which a bipolar transistor and a MOSFET (insulated gate field effect transistor) are formed on the same semiconductor substrate.
The present invention relates to a method of manufacturing a semiconductor device having a DD structure (Lightly Doped Drain structure).

[Conventional technology]

2. Description of the Related Art In recent years, bipolar transistors and MOSFETs have been formed on the same silicon substrate in semiconductor devices due to demands for higher speed and higher integration. Conventionally, this type of manufacturing method involves forming an n-type buried diffusion layer 2, a P-type buried diffusion layer 3, and an n-type epitaxial layer 4 on a p-type silicon substrate l, for example, as shown in FIG. Then, a field oxide film 11 is formed in the element isolation region other than the element activation region. Thereafter, a p-well 5 is formed, a gate oxide film 12 is formed, a gate electrode 13 of the MOSFET is provided, and low concentration diffusion layers 15 for the source and drain are formed by ion implantation.

Subsequently, an insulating film such as a silicon oxide film is grown on the entire surface of the wafer, and anisotropic etching is performed on the insulating film to form an insulating film sidewall 16 on the side surface of the gate electrode 13. After that, high concentration diffusion layers (not shown) for the source and drain are formed by ion implantation, and the MO of the LDD structure is formed.
Form an SFET.

Note that ion implantation is then performed using a photoresist as a mask to form a base diffusion layer of a bipolar transistor.

[Problem to be solved by the invention]

In the conventional manufacturing method described above, in order to make the MOSFET an LDD structure, a side wall 16 made of a silicon oxide film or the like is formed on the side surface of the gate electrode of the MOSFET by using anisotropic etching. base of the transistor.

A problem arises in that the surface of the substrate in the emitter formation region 9 is exposed to anisotropic etching, resulting in deterioration of characteristics of bipolar transistors to be formed later, and a decrease in yield.

An object of the present invention is to provide a method of manufacturing a semiconductor device that can form an LDD structure of a MOSFET without causing such deterioration of characteristics of a bipolar transistor.

[Means to solve the problem]

The method of manufacturing a semiconductor device of the present invention includes the steps of forming a field oxide film in the element bone MnM region of the semiconductor substrate and the base and emitter formation regions of the bipolar transistor;
After forming the gate electrode in the 3FET formation region, there is a process of forming low concentration source and drain diffusion layers on the source and drain of the MOS FET by ion implantation, and after growing an insulating film on the entire surface of the semiconductor substrate, this insulating film is A step of etching back the film by anisotropic etching to form a sidewall on the side surface of the gate electrode, a step of forming a high concentration source and drain diffusion layer by ion implantation using this sidewall, and a step of selectively forming a photoreceptor. A step of etching away the field oxide film in the base and emitter forming regions of the bipolar transistor using a resist as a mask, and selectively introducing impurities into the etched regions using the photoresist to form a base diffusion layer. The process includes a step of forming.

[Effect]

In the manufacturing method described above, the base and emitter regions of the bipolar transistor are covered with a field oxide film, and M
The sidewall of the gate electrode of the OSFET is formed, and then the field oxide film in the base and emitter formation regions is selectively removed to form the base diffusion layer of the bipolar transistor. Therefore, when forming the sidewall, the surface of the semiconductor substrate is You can't take damage.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1A to 1H are cross-sectional views showing the manufacturing process of a semiconductor device according to an embodiment of the present invention.

First, as shown in FIG. 5A, after forming an n-type buried diffusion layer 2 made of arsenic and a P-type buried diffusion layer 3 made of boron on a p-type silicon substrate 1, 5μ
An n-type epitaxial layer 4 having a thickness of about m is deposited.

Furthermore, in the formation region 10 of the n-channel MO3FET, p
Well 5 is provided. In this process, boron ions are implanted using a patterned photoresist or the like as a mask, and then a high temperature heat treatment is performed to form a well. and,
A nitride film 7 is further grown as an oxidation-resistant insulating film on the thermal oxide film 6 grown on the substrate surface, and using a photoresist pattern 8 as a mask, element isolation regions and base and emitter formation regions 9 of bipolar transistors are formed. The nitride film is removed by etching.

Next, as shown in FIG. 3B, selective oxidation is performed using the nitride film 7 as a mask to form a field oxide film 11 with a thickness of about 0.5 to 1.0 μm. This field oxide film 11 is formed in the element bone M region and in the base and emitter formation regions of the pievora transistor. After that, the nitride film 7. The thermal oxide film 6 is removed.

Next, as shown in the same figure (c), about 100 to 500 M
After forming the gate oxide film 12 of the O-puff ET, a polycrystalline silicon film doped with phosphorus is deposited.

Patterning is performed to form the gate electrode 13 of the MOSFET. Subsequently, photoresist 14 and gate electrode 13
Using this as a mask, phosphorus ions are implanted to form low concentration source and drain diffusion layers 15.

Next, as shown in FIG. 4(d), a side wall 16 of an oxide film is formed on the side surface of the gate electrode 13 of the MOSFET. This can be formed by growing an oxide film over the entire surface of the wafer and then etching back this oxide film by anisotropic etching. At this time, the base of the bipolar transistor.

Since the emitter formation region is covered with the field oxide film 11, the substrate surface thereof will not be damaged by anisotropic etching.

Next, as shown in FIG. 3(e), a photoresist 17, a gate electrode 13. Using the sidewall 16 as a mask, arsenic ions are implanted to form a highly concentrated source and drain diffusion layer 1.
form the sun. This causes the MOSFET to have an LDD structure.

Next, as shown in FIG. 5F, the field oxide film 11 in the base and emitter formation regions of the bipolar transistor is removed by etching using the patterned photoresist 19 as a mask, and boron ions are implanted using the photoresist 19 in parentheses as a mask. Then, the base diffusion layer 20 is formed.

Next, as shown in FIG. 4G, after a CVD oxide film 21 is grown over the entire surface of the wafer, an opening is formed in the emitter formation region. Next, a polycrystalline silicon film doped with arsenic is deposited and patterned to form an emitter electrode 22. Thereafter, arsenic is thermally diffused from the emitter electrode 22 into the epitaxial layer by heat treatment to form an emitter diffusion layer 23.

Next, as shown in the same figure (h), a PSG film 2 is formed as an interlayer film.
After growing 4, a contact hole is provided and an aluminum wiring 25 is formed to manufacture a semiconductor device.

Therefore, in this manufacturing method, the base and emitter regions of the bipolar transistor are covered with the field oxide film 11 during the formation of the sidewall 16 in the step shown in FIG. In fact, there is no deterioration in the characteristics of the bipolar transistor.

FIG. 2 is a sectional view of a part of the manufacturing process in another embodiment of the present invention.

That is, in this embodiment, as in the previous embodiment, FIG.
) to (c), the gate electrode 13. After forming the low concentration source and drain diffusion layers 15, a nitride film is grown on the entire surface of the substrate l as shown in FIG. 16A is formed.

Thereafter, a semiconductor device is manufactured according to the steps shown in FIGS. 1(e) to 1(h).

In this embodiment, a nitride film was used as the sidewall 16A, but when etching back the same, the base and emitter forming regions were etched to a thickness of 0.5 to 1.0 μm as in the previous embodiment.
Because it is covered with a field oxide film 11 that is relatively thick,
Regardless of the material of the sidewall, it will not be damaged by etching.

〔Effect of the invention〕

As explained above, in the present invention, since a field oxide film is formed in advance in the base and emitter formation regions of a bipolar transistor, when forming a sidewall on the side surface of the gate electrode of a MOSFET, silicon in the base and emitter formation regions is It is possible to prevent the substrate surface from being directly exposed to anisotropic etching, which has the effect of avoiding damage to the substrate surface and preventing deterioration of characteristics of bipolar transistors and reduction in yield.

In addition, the photoresist used to form the base diffusion layer of a bipolar transistor can be used as is to remove the field oxide film provided on the base and emitter formation regions by etching, and the base diffusion layer can be formed by ion implantation. Therefore, there is also the effect of preventing an increase in the number of photoresist patterning steps.

[Brief explanation of drawings]

FIGS. 1(a) to (h) are cross-sectional views showing one embodiment of the present invention in the order of manufacturing steps, FIG. 2 is a cross-sectional view showing a part of the manufacturing process of another embodiment of the present invention, and FIG. FIG. 2 is a cross-sectional view of a part of the manufacturing process for explaining a conventional manufacturing method. l...p-type silicon substrate, 2...n-type buried diffusion layer,
3... P-type buried diffusion layer, 4... N-type epitaxial layer, 5... P well, 6... Thermal oxide film, 7... Nitride film, 8... Photoresist, 9 ... Base, emitter formation region, 10 ... MO3FET formation region, 11
...Field oxide film, 12...Gate oxide film, 1
3... Gate electrode, 14... Photoresist, 15
...Low concentration source/drain region, 16.16A...
・Side wall, 17...Photoresist, 18・
...High concentration source, drain diffusion layer, 19...Photoresist, 20...Base diffusion layer, 21...CVD
Oxide film, 22... Emitter electrode, 23... Emitter diffusion layer, 24... PSG film, 25... Aluminum wiring. Figure Figure Figure 2 Figure Figure Number ↓ ↓ Ka↓ Number

Claims (1)

[Claims] 1. Bipolar transistor and LDD structure MOSFE
When manufacturing a semiconductor device in which T and T are formed on the same semiconductor substrate, there is a step of forming a field oxide film in the element isolation region of the semiconductor substrate and the base and emitter formation regions of the bipolar transistor, and forming a gate electrode in the MOSFET formation region. After that, a process of forming low concentration source and drain diffusion layers on the source and drain of the MOSFET by ion implantation, and growing an insulating film on the entire surface of the semiconductor substrate,
A step of etching back this insulating film by anisotropic etching to form a sidewall on the side surface of the gate electrode, a step of forming a highly concentrated source and drain diffusion layer by ion implantation using this sidewall, and selective formation. Using the photoresist as a mask, the field oxide film in the base and emitter formation regions of the bipolar transistor is etched away, and the photoresist is used to selectively introduce impurities into the etched areas to diffuse the base. 1. A method for manufacturing a semiconductor device, comprising the step of forming a layer.