JPS6235555A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To reduce the size and to increase the density of a semiconductor device by performing separation between polysilicon films by means of a polysilicon oxide film. 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 insulat ing film 13. Individual polysilicon films are separated therebetween by a normal locos method. After a thin polysilicon oxide film 15 is formed by thermal oxida tion, a nitride film 15 is accumulated and patterned. Then, a locus oxide film 17 is formed. The nitride film of a high resistor is removed. An oxide film 17' is formed by selective oxidation. After the film 16 is separated, high density ions are implanted to low resistors D, F. After an insulating film 18 is accumulat ed, it is treated at high temperature to form low resistors D', F'. Then, a contacting hole is opened, aluminum wiring electrode 19 is formed to complete a semiconductor device. The length of the resistor E' is shortened from L to L ' by lateral diffusion of an impurity at heat treating time for activating the ion implanted impurity.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a semiconductor device having a plurality of polysilicon films including a high resistance part (resistance element part) and a low resistance part (connection wiring part), and a semiconductor device thereof. This relates to a manufacturing method.

<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, a resist 5 is applied.

B is the high resistance circle. Remove the resist 5 and remove the insulating film 6.
After forming , heat treatment is performed to activate the ion-implanted impurities to form low resistance parts A' and σ. 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.

[Means to Solve the Problem] A plurality of polysilicon films are separated by a polysilicon oxide film, and the thickness of the polysilicon film in the high resistance part is made thinner than the thickness of the polysilicon film in the low resistance part. A first selective oxidation step for forming a polysilicon oxide film that separates polysilicon films, and a second selective oxidation step for thinning a high-resistance portion are provided.

<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 Deposit.

(2) Element isolation between individual polysilicon films is performed using the usual LOCOS method. Thin polysilicon oxide film 1 by thermal oxidation
After forming 5, a nitride film (5i3N4) 16 is formed by CVD method.
is deposited and patterned using a dry etching method. Then, using the nitride film 16 as an oxidation mask, a LOCOS oxide film 17 for isolation between polysilicon films is formed.

(3) Remove the nitride film in the high resistance area by etching.

(4) Selective oxidation (LOCOS method) is performed to form an oxide film 17'. After peeling off the nitride film 16, high concentration ions are implanted into F into the low resistance portion using the oxide film 17' as a mask for ion implantation. E is a high resistance part.

The oxide film 17' needs to have a thickness of 1000 A or more, considering the masking properties of ion implantation and the influence from the upper doped glass layer.

(5) After depositing the insulating film (doped glass layer) 18,
A high temperature treatment is performed to activate the ion-implanted impurities to form low resistance parts D' and F'. Next, contact holes are opened and aluminum wiring electrodes 19 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) E' is reduced from L to L' due to lateral diffusion of the impurities. Due to the height, the resistance value can be significantly increased compared to the initial film thickness d, and L' can be made smaller.

In the above embodiment, impurities are introduced to form the low resistance portion by ion implantation, but thermal diffusion may be used instead of ion implantation.

<Effects of the Invention> As explained in detail above, according to the present invention, the high resistance portion (
In a semiconductor device having multiple polysilicon films including a resistance element part) and a low resistance part (connection wiring part), the element dimensions of the high resistance part can be made extremely small. This makes it possible to downsize and increase the density of the device.

[Brief explanation of the drawing]

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. 11: Semiconductor substrate, 12: Active region, 13, 18: Insulating film, 14: Polysilicon film, 15
: Thin polysilicon oxide film, 16: Nitride film, 17.17
': LOCOS oxide film, 19; aluminum wiring electrode, D', F'
: low resistance part, E': high resistance part. Agent Patent Attorney Aihiko Fuku (and 2 others) Matter 11-P
Yu 3 and a half 1 resting straw first proverb F zomejo 1 field: C encouragement 1 picture

Claims (3)

[Claims] (1) In a semiconductor device having a plurality of polysilicon films including a high resistance part (resistance element part) and a low resistance part (connection wiring part), the separation between the plurality of polysilicon films is performed using a polysilicon oxide film. A semiconductor device characterized in that the polysilicon film thickness of the high resistance part is made thinner than the polysilicon film thickness of the low resistance part. (2) A semiconductor device having a plurality of polysilicon films including a high resistance part (resistance element part) and a low resistance part (connection wiring part), in which the separation between the plurality of polysilicon films is formed by a polysilicon oxide film. In the method for manufacturing a semiconductor device in which the polysilicon film thickness of the high resistance part is made thinner than the polysilicon film thickness of the low resistance part, for forming a polysilicon oxide film separating the polysilicon films. a first selective oxidation step, and a second selective oxidation step for thinning the high-resistance portion.
1. A method for manufacturing a semiconductor device, comprising: a selective oxidation step. (3) A patent characterized in that impurity ion implantation or impurity thermal diffusion for forming a low resistance part is performed using the polysilicon oxide film formed on the high resistance part by the second selective oxidation process as a mask. A method for manufacturing a semiconductor device according to claim (2).