Method for forming contact

Details Method for forming contact Method for forming contact

2003-11-25

2004-09-14

Nguyen, Tuan H. (Department: 2813)

Semiconductor device manufacturing: process

Coating with electrically or thermally conductive material

To form ohmic contact to semiconductive material

C438S258000, C438S637000

Reexamination Certificate

active

06790765

ABSTRACT:

FIELD OF INVENTION
The present invention relates to a method for forming contacts, and particularly, relates to a method for forming memory contacts on a semiconductor device.
BACKGROUND OF THE INVENTION
Most integrated circuits are manufactured by repeating several semiconductor processes, e.g. photolithographing, etching, depositing and doping, and are accomplished with many layers. To transmit signals among those layers, contacts and conductive lines are indispensable to modern semiconductor processes, especially for manufacturing memory chips. The contacts in a memory at least include bit-line contacts and gate contacts, and their manufacturing quality has great effect upon functions of the memory.
FIGS.
1
~
4
show the steps for forming contacts on a semiconductor device in the prior art. The contacts are positioned on a substrate
102
which has a bit-line contact area
100
and a gate contact area
200
.
FIG. 1A
shows the bit-line contact area
100
which includes a first polysilicon layer
104
, a conductive layer
106
, a first dielectric layer
108
, a side wall
110
, a second dielectric layer
112
, a third dielectric layer
114
, a fourth dielectric layer
116
and a second polysilicon layer
118
.
FIG. 1B
shows the gate contact area
200
which includes a third polysilicon layer
204
, the conductive layer
106
, a fifth dielectric layer
208
, the fourth dielectric layer
116
and the second polysilicon layer
118
.
Referring to FIG.
1
A and
FIG. 1B
, the method of the prior art coats a photoresist
120
on the bit-line contact area
100
as well as the gate contact area
200
, and then etches the two areas. Hence, a bit-line contact is formed on the bit-line contact area
100
as FIG.
2
A shows; however, a gate contact is not formed yet insofar as
FIG. 2B
shows. The method of the prior art needs further steps of coating another photoresist
210
on the gate contact area
200
, as
FIG. 3A
shows, and then etching the fifth dielectric layer
208
to form the gate contact as
FIG. 3B
shows.
This kind of semiconductor process causes the aspect ratio too small to facilitate photoresist removal.
SUMMARY OF THE INVENTION
The present invention provides a method for forming contacts on a semiconductor device, especially for forming memory contacts. The contacts mentioned herein are positioned on a substrate having a bit-line contact area and a gate contact area.
The method of the present invention includes the steps of forming an opening on the gate contact area, depositing a dielectric layer on the bit-line contact area and the opening, coating a photoresist to define a bit-line contact opening on the bit-line contact area and a gate contact opening on the gate contact area, etching the dielectric layer while using the photoresist as a mask to form the bit-line contact opening and the gate contact opening, removing the photoresist, and forming a conductive layer on the bit-line contact opening and the gate contact opening.


REFERENCES:
patent: 5019527 (1991-05-01), Ohshima et al.
patent: 5966602 (1999-10-01), Kawazu et al.
patent: 6271087 (2001-08-01), Kinoshita et al.
patent: 6348379 (2002-02-01), Wang et al.
patent: 2003/0211717 (2003-11-01), Seo et al.

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