Semiconductor device manufacturing: process – Chemical etching – Liquid phase etching
Reexamination Certificate
2000-10-31
2003-05-20
Kunemund, Robert (Department: 1765)
Semiconductor device manufacturing: process
Chemical etching
Liquid phase etching
C438S746000, C438S747000
Reexamination Certificate
active
06566275
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spinner apparatus with chemical supply nozzles and methods of forming patterns and performing etching using the same.
2. Description of the Related Art
In general, during processes for manufacturing semiconductor devices, electronic circuits are realized by performing certain functions by manipulating and controlling the order in which conductive layers, semiconductor layers, and insulating layers are stacked in combination with the shapes of patterns. In particular, in a semiconductor memory device and a semiconductor logic device, a plurality of unit chips having the same function and shape are repeatedly realized on the semiconductor wafer using a photomask designed for a certain purpose. Also, in the associated unit chips, a plurality of unit cells having the same shape are repeatedly formed in the unit chips in the form of a matrix.
As the semiconductor memory device and the semiconductor logic device become more highly integrated, the sizes of various patterns which constitute each device become even smaller. Accordingly, design rules are reduced to 0.35 &mgr;m, 0.25 &mgr;m, 0.18 &mgr;m, and 0.15 &mgr;m. However, contrary to the tendency of device patterns becoming smaller, the sizes of the semiconductor wafers are increasing to 6″, 8″, and 12″ to improve productivity. Correspondingly, sizes of photomasks are increasing to sizes such as 5″×5″, 6″×6″, and 9″×9″.
Therefore, in spite of the sizes of the device patterns being smaller, the sizes of substrates such as the semiconductor wafers or the photomasks are increasing. Accordingly, it is more difficult and important to form and manage the critical dimensions of the device patterns which are identically and repeatedly formed in the enlarged semiconductor wafer or photomask to be uniform all over the substrate. In particular, in the case of the photomask, it is more important to manage the uniformity of the critical dimension since the photomask operates as a disc for transcribing the image of the pattern formed on the photomask into the wafer.
FIG. 1
schematically shows the position of a spray-type nozzle
12
,
14
on the photomask
10
in a conventional photomask apparatus, in which steps of a developing process for forming the pattern on a photomask
10
are shown. Referring to
FIG. 1
, the photomask
10
is divided into a binary mask for controlling the intensity of light and a phase shift mask for simultaneously controlling the phase and intensity of light. Hereinafter, the binary mask will be described.
A schematic square blank substrate, in which a light shielding film
10
b
is formed on a substrate
10
a,
is provided. High purity synthetic quartz glass having characteristics of high light transmissivity and low thermal expansion is generally used as the substrate
10
a.
A multi-layer structure of metal chrome and chrome compound is generally used as the light shielding film
10
b.
The light shielding film
10
b
is coated with a resist layer
10
c.
In a positive-type E-beam resist, an electron beam decomposition type resist in which an organic solvent is used as a developing solution is mainly used as the resist layer
10
c.
In a negative-type E-beam resist, a chemical amplified resist (CAR) is used as the resist layer
10
c.
An exposing process is performed on the resist layer
10
c
using an exposure apparatus according to the designed pattern. A raster scan type apparatus and a vector scan apparatus in which a spot beam is used are commonly used as the exposure apparatus. An exposing apparatus using a multi-beam is typically used. In
FIG. 1
, reference numeral
10
c′
denotes the exposure region of the resist layer which is exposed to light and creates a chemical reaction.
A designed resist pattern is formed by developing and removing the exposure region
10
c′
of the resist layer using the developing solution. Then, an etching process is performed on the light shielding film
10
b
using the resist pattern as the etching mask and a remaining resist pattern material is removed. Accordingly, a predetermined light shielding film pattern is formed on the substrate
10
a.
Therefore, a desired photomask is manufactured.
In the processes of manufacturing the photomask, the exposing process and the developing process are most important in determining the CD uniformity of the mask. In the exposing process, the uniformity of the CD is dependent on the reproducibility of pparatuses when a writing method, a substrate, and an accelerating voltage are determined in the exposing apparatus. Meanwhile, in the developing process, the uniformity of the CD can vary according to a developing apparatus and a developing method.
FIG. 1
shows one conventional process of manufacturing the photomask. In the developing process, the developing solution is supplied to the photomask
10
on which the exposing process is performed, thus developing the exposure region
10
c′
. The developed exposure region
10
c′
is then removed. The developing solution is sprayed by a first spray-type nozzle
12
and a second spray-type nozzle
14
. At this time, the photomask
10
is fixed horizontally to the fixing chuck (not shown) of a rotating spinner and rotates at a certain speed.
FIG. 2
is a plan view of
FIG. 1
, which shows the positions of the first spray-type nozzle
12
and the second spray-type nozzle
14
which are positioned on the photomask
10
.
According to the conventional spin spray developing process, the resist pattern formed on the square photomask
10
rapidly changes in a concentric circle direction from the rotation center of the spinner. This is because various processing conditions in the rotation center do not coincide with those in the rotation edge since the photomask rotates in a state of being fixed to the fixing chuck of the spinner and the developing process is performed using fluid chemicals. Therefore, research on methods for improving the uniformity of the CD by maintaining the processing conditions all over the substrate such as the photomask and the wafer have been continuously required.
Results of comparing various methods of the developing process which greatly affect the uniformity of the CD are disclosed in “Study of Development Methods For Chemical Amplification Resist” Hidetaka Saito, et al, SPIE Vol. 3412, pp. 269-278, 1998. According to this article, when the deviation of the CD is measured after performing the developing process by a conventional shower-spray development method, a puddle development method, and a dip development method, the deviation of the CD (3&dgr;) is 17 nm, in the case of the dip development method. However, in the case of the dip development method, the developing solution must be renewed at all times in order to maintain a low level of defects in the mask. Accordingly, a large amount of developing solution is necessary, which is not economical. Therefore, a soft-shower development method in which the spray pressure of the developing solution is changed is disclosed the above article. However, problems of the developing process of the conventional spin-spray method are not completely solved since processing conditions in the center of the substrate, i.e., the center of the rotation, are different from those at the edge of the substrate, which is significantly affected by the centrifugal force caused by the rotation.
SUMMARY OF THE INVENTION
To solve the above problem, it is an object of the present invention to provide a spinner apparatus with chemical supply nozzles capable of improving the critical dimension uniformity of a pattern formed on a substrate during a developing process or an etching process, which is performed by a spin method using chemicals.
It is another object of the present invention to provide a method for forming a pattern, capable of improving the critical dimension uniformity of the pattern formed on the substrate during the developing process performed by the spin
Kunemund Robert
Mills & Onello LLP
Samsung Electronics Co,. Ltd.
Tran Binh X.
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