JPS6235554A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To reduce the size and to increase the density of a semiconductor device by reducing the thickness of a polysilicon film of a high resistor as compared with that of a polysilicon film of a low resistor. CONSTITUTION:After an active region 12 is formed on a semiconductor substrate 11, a polysilicon film 14 is accumulated on the entire surface through an insulating film 13, and patterned. After a thin polysilicon oxide film 15 is formed by thermal oxidation, a nitride film 16 is accumulated, and patterned by a dry etching method. With the film 16 as an oxide mask a locos oxide film D is formed. After the film 16 is separated, with the film D as a mask of implanting ions high density ions are implanted to low resistors E, G. After an insulating film 17 is accumulated, it is treated at high temperature to form low resistors E', G'. Then, a contacting hole is opened, aluminum wiring electrode 18 is formed to complete a semiconductor device. The resistance value can be increased in order as compared with that at initial film thickness (d), and L' can be reduced.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a semiconductor device having a polysilicon film including a high resistance part (resistance element part) and a low resistance part (connection wiring part), and a method for manufacturing the same. It is related to.

<Prior Art> With the recent integration of LSIs, semiconductor elements have been used as load elements in cells, for example, in static type memory elements.

Resistance elements are often formed from polysilicon because of the simplicity of the process.

FIG. 2 shows an example of the structure of a conventional semiconductor device and its manufacturing process.

After forming an active region 2 on a semiconductor substrate 1, a polysilicon film 4 is formed on the entire surface with an insulating film 3 interposed therebetween.

After patterning the polysilicon film 4, high concentration As or P ions are implanted using the resist 5 as a mask to form low resistance parts (connection wiring parts) A and C. BX is a high resistance section. After removing the resist 5 and forming an insulating film 6, heat treatment is performed to activate the ion-implanted impurities to form low resistance parts A' and C'. After opening the contact holes, aluminum wiring electrodes 7 are provided to complete the semiconductor device. During heat treatment for activating the ion-implanted impurities, the length of the high resistance portion (resistance element portion) B' is reduced from L to L' due to lateral diffusion of the impurities. The high resistance value is determined by L'.

<Problems to be Solved by the Invention> However, the conventional semiconductor device described above has a problem in that the element size of the high resistance portion becomes large due to the control of the high resistance value.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a semiconductor device in which the element size of the high resistance portion is extremely small, and a method for manufacturing the same.

The only way to solve the problem is to make the polysilicon film thickness of the high resistance part thinner than the polysilicon film thickness of the low resistance part. The high resistance portion is formed by partially thinning the polysilicon film by selective oxidation.

<Example> FIG. 1 shows the structure of a semiconductor device and its manufacturing process according to the present invention.

(1) After forming the active region 12 on the semiconductor substrate 11, a polysilicon film 14 is formed on the entire surface with a film thickness of 3000 nm with an insulating film 13 interposed therebetween.
A is deposited and patterned.

(2) After forming a thin polysilicon oxide film 15 by thermal oxidation, a nitride film (Si3N4) 16 is deposited by CVD and patterned by dry etching.

(3) A LOCOS oxide film is formed using the nitride film 16 as an oxidation mask. After peeling off the nitride film 16, the low resistance portion E is formed using the oxide film as a mask for ion implantation.

High concentration ion implantation into G. F is a high resistance part. The oxide film needs to be 1000 A or more, considering the masking properties of ion implantation and the influence from the upper doped glass layer.

(4) After depositing the insulating film (doped glass layer) 17,
High-temperature treatment is performed to activate the ion-implanted impurities,
Low resistance parts E' and G' are formed. Next, contact holes are opened and aluminum wiring electrodes 18 are provided to complete the semiconductor device.

During the heat treatment for activating the ion-implanted impurities, the length of the high resistance portion (resistance element portion) F' is reduced from L to L' due to lateral diffusion of the impurities. The high resistance value is determined by L' in the length direction and by the polysilicon film thickness d' after selective oxidation in the thickness direction.

By setting d'<200OA, the resistance value can be increased in an orderly manner compared to the initial film thickness d, and L
′ can be made smaller.

In the above embodiment, impurities are introduced to form a low resistance part by ion implantation, but thermal diffusion may also be used instead of ion implantation. According to the invention, the high resistance part (
In a semiconductor device having a polysilicon film including a resistance element part) and a low resistance part (connection wiring part), the element size of the high resistance part can be made extremely small.
This achieves miniaturization and higher density of semiconductor devices.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the structure of a semiconductor device and its manufacturing process according to the present invention, and FIG. 2 is a diagram showing an example of the structure of a conventional semiconductor device and its manufacturing process. Explanation of symbols 11: semiconductor substrate, 12: active region, 13.17: insulating film, 14: polysilicon film, 15:
Thin polysilicon oxide film, 16: nitride film, 18 Ni aluminum wiring electrode, D: LOCOS oxide film, E', G': low resistance part,
F': High resistance part. Agent Patent attorney Aihiko Fuku (and 2 others) Mo 1ll
121

Claims (3)

[Claims] (1) In a semiconductor device having a polysilicon film including a high resistance part (resistance element part) and a low resistance part (connection wiring part), the polysilicon film thickness of the high resistance part is determined by the polysilicon film thickness of the low resistance part. A semiconductor device characterized by being thinner than a silicon film. (2) A semiconductor device having a polysilicon film including a high resistance part (resistance element part) and a low resistance part (connection wiring part), wherein the polysilicon film thickness of the high resistance part is equal to the polysilicon film thickness of the low resistance part. 1. A method of manufacturing a semiconductor device which is made thinner than a silicon film, characterized in that the high resistance portion is formed by partially thinning a polysilicon film using a selective oxidation method. (3) A claim characterized in that impurity ion implantation or impurity thermal diffusion for forming a low resistance part is performed using a polysilicon oxide film formed on a high resistance part by a selective oxidation method as a mask. The method for manufacturing a semiconductor device according to item (2).