Fluid sprinkling – spraying – and diffusing – Unitary plural outlet means – Arranged in plural groups or rows
Reexamination Certificate
2000-03-09
2004-09-28
Nguyen, Dinh Q. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Unitary plural outlet means
Arranged in plural groups or rows
C239S554000, C239S567000, C239S548000, C427S240000
Reexamination Certificate
active
06796517
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the field of semiconductor integrated circuits. The invention is illustrated in an example with regard to a semiconductor integrated circuit wet processing method and apparatus, but it will be recognized by those of skill in other arts that the invention has a wider range of applicability. Merely by way of example, the invention can also be applied to the manufacture of raw wafers, disks and heads, flat panel displays, microelectronic masks, and other applications requiring high purity wet processing such as steps of rinsing, drying, and the like. The present invention generally relates to a nozzle and a method for dispensing process liquids onto a surface. More particularly, the present invention relates to a fluid dispense nozzle for dispensing fluids of photoresist developer chemicals, photoresist chemicals, cleaning and rinsing chemicals, etchant chemicals, or dielectric chemicals onto a rotating semiconductor substrate material.
Integrated circuits are typically constructed by depositing a series of individual layers of predetermined materials on a wafer shaped semiconductor substrate, or “wafer.” The individual layers of the integrated circuit are in turn produced by a series of manufacturing steps. For example, in forming an individual circuit layer on a wafer containing a previously formed circuit layer, an oxide, such as silicon dioxide, is deposited over the previously formed circuit layer to provide an insulating layer for the circuit. A pattern for the next circuit layer is then formed on the wafer using a radiation alterable material, known as photoresist. Two very common families of photoresists are phenol-formaldehyde polymers and polyisoprene polymers.
Photoresist materials are generally composed of a mixture of organic resins, sensitizers and solvents. Sensitizers are compounds, such as bio-aryldiazide and o-naphthaquinone-diazide, that undergo a chemical change upon exposure to radiant energy, such as visible and ultraviolet light resulting in an irradiated material having differing solvation characteristics with respect to various solvents than the nonirradiated material. Resins are used to provide mechanical strength to the photoresist and the solvents serve to lower the viscosity of the photoresist so that it can be uniformly applied to the surface of the wafers.
After a photoresist layer is applied to the wafer surface, the solvents are evaporated and the photoresist layer is hardened, usually by heat treating the wafer. The photoresist layer is then selectively irradiated by placing a radiation opaque mask containing a transparent portion defining the pattern for the next circuit layer over the photoresist layer and then exposing the photoresist layer to radiation. The photoresist layer is then exposed to a chemical, known as developer, in which either the irradiated or the nonirradiated photoresist is soluble and the photoresist is removed in the pattern defined by the mask, selectively exposing portions of the underlying insulating layer. Common developers are tetramethyl ammonium hydroxide, sodium hydroxide, xylene and Stoddard solvent. After development rinsing is performed with fluids such as water or n-Butylacetate.
The exposed portions of the insulating layer are then selectively removed using an etchant to expose corresponding sections of the underlying circuit layer. The photoresist must be resistant to the etchant, so as to limit the attack of the etchant to only the exposed portions of the insulating layer.
Alternatively, the exposed underlying layer(s) may be implanted with ions which do not penetrate the photoresist layer thereby selectively penetrating only those portions of the underlying layer not covered by the photoresist. The remaining photoresist is then stripped using either a solvent, or a strong oxidizer in the form of a liquid or a gas in the plasma state. The next layer is then deposited and the process is repeated until fabrication of the semiconductor device is complete.
Photoresist solution, developer solution and other process liquids are typically applied to the wafer using a spin coating technique in which the process liquid is sprayed on the surface of the wafer as the wafer is spun on a rotating chuck. The spinning of the wafer distributes the liquid over the surface of the material. In particular, when developer chemicals are applied to the surface, it is necessary to quickly and gently produce a deep puddle of developer on the wafer to ensure that the photoresist layer is dissolved uniformly in areas that are soluble in the developer. In a developing process, among other manufacturing processes for a semiconductor device, a developer should be uniformly applied to a resist film on a semiconductor wafer within a predetermined time. The reason is that the developing uniformity for the resist film is generally supposed to depend on the state of development, so that the development is subject to irregularity unless the developer is first uniformly supplied to the whole surface of the wafer. Conventionally, therefore, liquid coating nozzles of various types have been proposed.
U.S. Pat. No. 4,267,212 discloses a process for spin coating a semiconductor wafer uniformly with a coating solution such as a photographic emulsion by rotating the wafer at a first speed while simultaneously applying the coating solution through a circular nozzle at a radially moving position. Once the semiconductor wafer has been initially covered, the speed of rotation of the wafer is increased and rotation continues until a uniform coating has been obtained. A similar process having a stationary nozzle is disclosed in U.S. Pat. No. 3,695,928.
In each of the aforedescribed apparatuses and methods, the fluid coating material is dispensed in a column of fluid whose cross-section approximates a circle, either during wafer rotation or while the wafer is stationary. Wafer coating is achieved by building up a pool of the fluid coating material in the nature of a thick layer and spin casting a film thereof by accelerating the rotation of the wafer about its own center in order to remove the excess material and to leave a thin film coating therebehind. The amount of fluid coating material, such as photoresist, remaining on the wafer is known to be a very small fraction of the amount that is initially dispensed, approximately one part in one thousand. This results in a substantial material loss of unusable photoresist along with its attendant cost. In addition, this creation of a pool of the fluid coating material on the wafer surface can result in the formation of uneven films which might adversely effect subsequent wafer processing.
Very specifically, in the prior art, a variety of devices, called nozzles, are used to apply fluids to a wafer surface. In
FIG. 1
, a simple spout nozzle
5
is depicted with an orifice
10
at the end of a spout attached to a fluid supply tube
15
. The nozzle is positioned above the center of a rotating wafer
20
shown in the plan view.
FIG. 2
depicts a side view of this device dispensing fluid
31
onto the wafer
20
supported by a spin chuck
33
connected to a motor (not shown) that rotates the chuck and thus the wafer. In this nozzle
5
, the fluid reaches the wafer center
35
first and only gradually is dispersed by centrifugal force to the perimeter
37
of the wafer. In fact, even after distribution to the perimeter, a greater amount of developer remains near the center
35
as shown in FIG.
3
.
FIG. 4
depicts a cross-sectional view along a longitudinal axis of another version of the prior art, known as a block nozzle
55
, which tries to solve some of the difficulties of the spout nozzle. In this case, the block nozzle
55
is a rectangular vessel
40
with an interior
42
serving as a liquid reservoir. The nozzle's top surface
44
has two inlet fittings
46
A, B for attachment to a fluid supply tube
48
A, B, a support
41
for connection to an external apparatus not depicted, and an outlet fitting
43
for attachment to a gas outlet tube. Th
Advanced Micro Devices , Inc.
Eschweiler & Associates LLC
Nguyen Dinh Q.
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