Method for forming a trench isolation structure

Details Method for forming a trench isolation structure Method for forming a trench isolation structure

2002-12-27

2004-09-21

Smith, Matthew (Department: 2825)

Semiconductor device manufacturing: process

Formation of electrically isolated lateral semiconductive...

Having air-gap dielectric

C438S427000

Reexamination Certificate

active

06794266

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method for forming a trench isolation structure, and more particularly to a method for forming a shallow trench isolation structure (STI) with high aspect ratio (AR).
2. Description of the Related Art
Recently, as the manufacturing techniques of semiconductor integrated circuits develop, the number of devices in a chip increases. The size of the device decreases as the degree of integration increases. However regardless of the reduction of the size of the device, adequate insulation or isolation must be formed among individual devices in the chip so that good device characteristics can be achieved. This technique is called device isolation technology. Among different device isolation techniques, local oxidation of silicon (LOCOS) and shallow trench isolation (STI) manufacturing methods are the two most used methods. In particular, as the latter has a small isolation region and can keep the substrate level after the process is finished, it is the semiconductor manufacturing method obtaining the most attention.
In the conventional STI method, an insulating layer is filled in the trench of the substrate by chemical vapor deposition (CVD). Thereafter, the excess insulating layer deposited on the substrate is removed. However, since the aspect ratio of the trench is raised by increasing the integration of the integrated circuit, the conventional deposition apparatus cannot completely fill the trench with insulating layer due to insufficient gap filling ability. Accordingly, poor insulation results, degrading the reliability of the device.
FIGS. 1
a
to
1
c
are cross-sections of the conventional method for forming a shallow trench isolation structure. First, in
FIG. 1
a
, a substrate
100
, such as a silicon wafer, is provided. Next, a pad oxide layer
102
, a pad nitride layer
104
and a patterned photoresist layer
106
are successively formed on the substrate
100
. The patterned photoresist layer
106
has a plurality of openings
106
a
to expose the pad nitride layer
104
.
Next, in
FIG. 1
b
, the pad nitride layer
104
, the pad oxide layer
102
, and the substrate
100
under the openings
106
a
are successively etched to form trenches
108
with high aspect ratio (AR≧3) in the substrate
100
. Thereafter, the patterned photoresist layer
106
is removed.
Finally, in
FIG. 1
c
, a silicon oxide layer
110
formed by high-density plasma CVD (HDPCVD) is deposited on the pad nitride layer
104
and in the trenches
108
. However, since the conventional CVD apparatus with insufficient gap filling ability cannot completely fill the trenches
108
with HDP oxide layer
110
, voids
110
a
are created in the HDP oxide layer
110
in the trenches
108
. As a result, poor isolation between devices reduces the reliability of the devices.
SUMMARY OF THE INVENTION
Accordingly, an object of the invention is to provide a method of forming a shallow trench isolation structure using an insulating material with good gap filling ability to fill in the trench, thereby reducing the aspect ratio of the trench to prevent voids or seams in the shallow trench isolation structure.
To achieve these and other advantages, the invention provides a method of forming a shallow trench isolation structure. First, a substrate having at least one trench of aspect ratio more than 3 is provided. Next, the trench is filled with a spin on glass (SOG) layer. Thereafter, a baking is performed on the SOG layer at below 400° C. for 30~60 min. Next, the SOG layer is etched back to a predetermined depth using buffer oxide etch solution (BOE). The proportional volume of ammonium fluoric (NH
4
F) to hydrofluoric (HF) acid in BOE is about 50~200:1. Next, a curing is performed on the remaining SOG layer at 750° C.~1000° C. for 30~60 min. The highest temperature of the curing is based on the temperature of subsequent annealing, and both temperatures are substantially equal. Next, an insulating layer is formed on the remaining SOG layer to fill the trench completely. The insulating layer can be high-density oxide. Finally, the insulating layer is annealed.


REFERENCES:
patent: 5801082 (1998-09-01), Tseng
patent: 5830797 (1998-11-01), Cleeves
patent: 6232228 (2001-05-01), Kwag et al.
patent: 6479376 (2002-11-01), Huang et al.
patent: 6566229 (2003-05-01), Hong et al.
patent: 6596607 (2003-07-01), Ahn
patent: RE38363 (2003-12-01), Gocho et al.
patent: 6699799 (2004-03-01), Ahn et al.
patent: 2003/0054616 (2003-03-01), Endisch et al.
patent: 404067634 (1992-03-01), None
patent: 404152551 (1992-05-01), None

Affiliated with

Also associated with

Rating

Method for forming a trench isolation structure does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method for forming a trench isolation structure, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for forming a trench isolation structure will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3203763