Browse Prior Art Database

Dielectric Isolation of Silicon Devices

IP.com Disclosure Number: IPCOM000083550D
Original Publication Date: 1975-Jun-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Badami, AV: AUTHOR [+2]

Abstract

Fig. 1 shows a method of establishing dielectric isolation of silicon devices, which consists of two P+ diffusions 4 and 6, respectively, on substrate 8 and epitaxial layer 10, and an electrochemical etching process to convert the P diffused material to porous material. After the P material is made porous, it is oxidized, which provides the necessary dielectric for device isolation.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 79% of the total text.

Page 1 of 2

Dielectric Isolation of Silicon Devices

Fig. 1 shows a method of establishing dielectric isolation of silicon devices, which consists of two P+ diffusions 4 and 6, respectively, on substrate 8 and epitaxial layer 10, and an electrochemical etching process to convert the P diffused material to porous material. After the P material is made porous, it is oxidized, which provides the necessary dielectric for device isolation.

Another method of producing dielectric isolation of silicon devices, is to convert the entire surface of the substrate to a porous material to a depth of 3 micron by electrochemical etching (Fig. 2). The appropriate epitaxial layer 12 is then deposited on top of the porous surface (Fig. 3). Device patterns are placed on the epitaxy using standard photolithography and masking techniques (Fig. 4).

Another electrochemical etch is placed between the devices, which extends the porous region into the previously etched substrate surface (Fig. 5). The entire device is then oxidized (14), which converts the porous area into SiO(2) to complete the isolation (Fig. 6).

The advantages to this technique are the elimination of two diffusions and reduced exposure to thermal cycling.

In addition, the epitaxial silicon film (layer) on a porous silicon structure (Figs. 2 and 3) reduces slip lines and line dislocations through electrochemical surface preparation.

The substrate surface is electrochemically etched using > 10% HF solution and 10mA/cm/2/, causing the t...