Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – Having insulated gate
Reexamination Certificate
1999-06-30
2001-08-07
Chaudhari, Chandra (Department: 2813)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
Having insulated gate
C438S253000, C438S396000, C438S964000
Reexamination Certificate
active
06271086
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the improvement of HSG (Hemispherical silicon grain), and more specifically relates to preventing the cluster defect of HSG by heat treatment.
2. Description of the Prior Art
HSG is broadly applied in contemporary semiconductor fabrication. The most famous application of HSG is forming HSGs on surface of bottom electrode of capacitor to efficiently increase total surface area of electrode of capacitor.
In addition, in most of applications of HSG, when HSGs (Hemispherical Silicon Grains) are formed on a wafer, then wafer with HSGs are directly cleaned before any following fabrication such as deposition of dielectric layer. For example, when HSGs are used to increase surface area of electrode of capacitor, HSGs are pre-cleaned before formation of dielectric layer. Herein, cleaning process is used to wipe out any impurity on the wafer and is more especially to wipe out any impurity on HSGs. No matter how, an obvious defect is found that during cleaning process a plurality of clusters appear on surface of HSGs. In other words, parts of HSGs are covered by these clusters and then yield of following fabrication is decreased by these clusters. No matter how, mechanism of formation of clusters still is an unsolved question, and a main component of these clusters is silicon.
FIG. 1A
to
FIG. 1C
are some qualitative illustrations show how formation of HSG and clusters defect are formed by conventional fabrication.
First as
FIG. 1A
shows, dielectric layer
12
is formed on substrate
10
and is patterned to form a plurality of gaps inside dielectric layer
12
. Therefore, conductive layer is formed on dielectric layer
12
and completely fills all of gaps. Then, conductive layer is patterned to form a plurality of conductive structures
14
, where each conductive structure
14
completely fills one gap. In addition, possible material of conductive structures
14
comprises polysilicon, silicon and so on. No matter how, in order to form HSG on conductive structures
14
in following process, it is better to be formed conductive structures
14
by polysilicon.
As
FIG. 1B
shows, HSGs
16
are formed on conductive structures
14
and main function of HSGs
16
is increasing total surface area of conductive structures
14
.
Therefore, HSGs
16
and dielectric layer
12
are directly cleaned just when HSGs
16
are formed, clusters
18
are obviously formed on HSGs
16
, as
FIG. 1C
shows. Where material of clusters
18
comprises Si. In addition, cleaning solution of said cleaning process comprises HF and nitric acid.
The disadvantage of clusters
18
can be explained by an example, as
FIG. 1D
shows. When oxide layer
19
is formed on dielectric layer
12
and totally covers conductive structures
14
and HSGs
16
, it is obvious that the interactive area between HSGs
16
and oxide layer
19
is decreased by cluster
18
, and then interaction between HSGs
16
and oxide layer
19
is degraded by the cluster defect
According to previous discussion, it is obvious that cluster defect is a serious disadvantage in application of HSG and then it is desired to develop a method to overcome the cluster defect.
SUMMARY OF THE INVENTION
The primary object of the present invention is to propose a method capable of preventing the cluster defect of HSG.
A further object of the present invention is to propose a method that efficiently prevents formation of cluster during cleaning process.
In order to accomplish these objects of the invention, a method capable of preventing cluster defect by heat treatment is proposed. The proposed method comprises following steps:
First, forming HSGs on some semiconductor structures, where these semiconductor structures are formed in and on a wafer.
Second, dealing wafer with HSGs by a heat treatment. Where required temperature of heat treatment does not need to be a high temperature, and heat treatment can be provided by rapid thermal process, furnace, and so on.
Third, cleaning wafer with HSGs by cleaning solution. Owing to the fact that HSGs are pre-heated before the cleaning process, no cluster is formed on HSGs and then cluster defect is prevented.
Obviously, the characteristic of the invention is that a heat treatment process is used to treat HSGs before the cleaning process is used to eliminate impurity.
REFERENCES:
patent: 5721153 (1998-02-01), Kim et al.
patent: 5930625 (1999-06-01), Lin et al.
patent: 5981351 (1999-06-01), Nam et al.
patent: 6087226 (2000-07-01), Kim et al.
Hsia Da-Wen
Huang Cheng-Chiech
Lin Kuo-Chi
Chaudhari Chandra
Huynh Yennhu B.
United Microelectronics Corp.
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