WO2002000957A2

WO2002000957A2 - System for delivering a vapor and method

Info

Publication number: WO2002000957A2
Application number: PCT/US2001/019217
Authority: WO
Inventors: Sheshraj Tulshibagwale; Dmitry Lubomirsky; Simon Yavelberg; Yoshio Watanabe; Saravjeet Singh
Original assignee: Applied Materials, Inc.
Priority date: 2000-06-23
Filing date: 2001-06-14
Publication date: 2002-01-03
Also published as: WO2002000957A3

Abstract

Highly efficient conversion of a liquid (43) to a vapor can be carried out in a vessel (42) that is transparent to infrared energy by mounting an infrared lamp (46) adjacent to the vessel. The liquid absorbs light from the infrared lamp, heating the liquid. Heating can be further facilitated by immersing opaque dielectric bodies (44), such as polytetrafluoroethylene or ceramic spheres, in the liquid. The light energy from the lamp is absorbed by the dielectric bodies, energy, heating the bodies and in turn further heating the liquid in which they are immersed. The vaporized liquid can be passed to a processing chamber.

Description

SYSTEM FOR DELIVERING A VAPOR AND METHOD

This invention relates to a system and method for

vaporizing a liquid. More particularly, this invention relates

to a system and method for efficiently transmitting energy

from an infrared light source to a liquid in order to vaporize

the liquid.

BACKGROUND OF THE INVENTION

Organic photoresists are widely used in the semiconductor

industry to pattern underlying layers. Photoresists, when

struck by a patterned light beam, either polymerize or

decompose, changing their solubility with respect to a

developer solvent. After development, the solubilized

photoresist areas are dissolved in the developer solvent,

leaving a pattern of insoluble material on the exposed

substrate.

The patterned substrate is then processed, either to

deposit materials in the openings in the photoresist layer, or

to etch the portions of the substrate that are exposed. At the

end of this step, the remaining portions of the photoresist

must be removed. This is often done by ashing, or treatment

with an oxygen plasma, to decompose the remaining organics.

This is known as stripping or ashing the photoresist. Further, since the portions of the substrate where the photoresist have been removed must generally be passivated in

order to prevent reaction of the exposed layer with air or

oxygen, a passivation layer is deposited over these portions. For example, the substrate can be treated with a mixture of oxygen, nitrogen and water vapor to deposit a polymeric passivation layer over the exposed portions of the substrate.

A chamber has been developed for carrying out the above

reaction steps, known as the advanced strip and passivation (ASP) chamber. Such a chamber is shown in Fig. 1.

The advanced strip and passivation chamber 10 includes a

substrate support 12 which can be temperature controlled. A

substrate 14 to be processed is mounted on the support 12. Spaced from and opposed to the support 12 is a first gas inlet plate 16, including a plurality of openings for passage of a

processing gas through the openings. A second gas inlet plate

18, also having a plurality of openings therein, is ^' connected

to but spaced from the first inlet plate 16. Processing gas is passed into a gas inlet 20, which passes a source of microwave energy 22. As the inlet gas or gases passes the microwave source 22, a plasma is formed from the gases, which plasma is

passed through the inlet plates 16 and 18 into the processing chamber 10. The chamber 10 is evacuated through outlets 24.

In a prior art chamber, the gas inlet plates 16, 18, are

made of quartz. However, if fluorine is to be added to the

processing gas, for example to enhance the removal of

polymeric material on the sidewalls of openings in the

substrate 14, the gas inlet plates 16, 18 are made of a

ceramic, such as alumina, instead. Ceramics are not etched by

fluorine .

The ASP chamber is generally used thus for several

purposes; to remove photoresist, to passivate the exposed

surface of a wafer substrate, and to remove or soften sidewall

polymer in openings formed in the substrate . The present

etchant mixture for ashing and passivating the surface of the

substrate comprises a mixture of oxygen, nitrogen and water

vapor. However, water must be heated above its vaporization

temperature in order to add water as a vapor to the processing

chamber along with other processing gases. This has been done

by resistive heating. However, this is not an efficient way to

vaporize water, which requires a lot of energy. Thus an

improved method of generating a vapor from a liquid for

delivery to an ASP or other processing chamber has been

sought . SUMMARY OF THE INVENTION

We have found a method of transmitting energy from an

infrared lamp light source to a liquid contained in a vessel

that is infrared transparent, in order to vaporize the liquid

prior to delivering its vapor to a processing chamber. The

infrared lamp is mounted adjacent to a vessel that is made of

a material that is transparent to infrared light, such as

quartz, which vessel contains the liquid to be vaporized. A

plurality of small, opaque, inert, dielectric bodies are

immersed in the liquid in the vessel. These dielectric bodies

also absorb light energy from the light source, heating the

dielectric bodies, and transmit the heat energy directly to

the liquid in the vessel . This avoids direct contact between

the liquid and the light source and greatly improves the

efficiency of heating a liquid such as water to its

vaporization temperature. A light reflector, mounted on the

outside of the quartz vessel and opposite the infrared light

source, directs the infrared light energy back to the liquid

in the vessel. This reflector prevents the light energy from '

being dissipated outside the vessel, further improving the

efficiency of the system. BRIEF DESCRIPTION OF THE DRAWING

Fig. 1 is a cross sectional view of an advanced strip and

passivation chamber of the prior art .

Fig. 2 is a cross sectional view of a water vapor

delivery system of the invention for delivery to a processing

chamber .

DETAILED DESCRIPTION OF THE INVENTION

The present method provides a means of generating heat by

means of an infrared light source, e.g., an infrared lamp,

mounted outside a light transparent vessel that contains a

liquid to be vaporized. The light passes into the vessel,

which can be made suitably of quartz, where the light energy

is absorbed by the liquid. The invention is further described

using water as the liquid to be vaporized, but any aqueous

solution or other liquid can be substituted as desired.

The light transparent vessel is partially filled with a

liquid to be vaporized. The vessel also includes a plurality

of small, opaque dielectric bodies immersed in the liquid.

These bodies also absorb infrared light energy from the lamp'

and become heated. The heated bodies further heat the liquid,

adding to the efficiency of the method.

The opaque dielectric bodies are suitably made from an opaque dielectric, such as a ceramic, which can be alumina or

aluminum nitride, or a polymer such as

polytetrafluoroethylene . As the light is absorbed by the

liquid and the dielectric bodies, the liquid and the

dielectric bodies become heated, eventually to the

vaporization temperature of the liquid. These dielectric

bodies also serve as nucleation sites for the formation of

small bubbles of the liquid during heating, aiding in the

vaporization process and improving the efficiency of

vaporization.

On an exterior wall of the vessel opposite to the heating

lamp, a reflector or opaque covering, such as of aluminum

foil, acts to reflect light energy that would otherwise escape

the liquid back into the infrared absorbing vessel. This still

further improves the overall efficiency of the present system

and method.

The water vapor delivery system 40 of the invention is

shown in Fig. 2.

A quartz or other infrared light transparent vessel 42 is

partially filled with a liquid 43 to be vaporized. The liquid

43 contains a plurality of bodies 44 made of a material that

absorbs infrared energy immersed therein. The liquid 43 and the bodies 44 absorb energy from an infrared lamp 46 mounted

outside of the light transparent vessel 42. A reflector 48,

such as a metal foil sheet, is mounted on the outside of the

vessel 42, opposite to the lamp 46, to prevent light energy

from passing through the quartz vessel 42 where it will be

lost to the system. Instead, the light energy is reflected or

re-directed back into the liquid 43 by the reflector 48.

In order to further improve the efficiency of the system,

as shown in Fig. 2, one lamp 46 may be used to heat two

infrared light absorbing vessels 42.

By using an infrared transparent vessel, the infrared

light from the lamp is permitted to pass into the vessel and

the liquid to be vaporized, avoiding direct contact between

the infrared lamp and the liquid. Thus an efficient transfer

of the light energy from the lamp to the liquid occurs.

Infrared light is also absorbed by the dielectric bodies in

the vessel, which in turn become heated and further heat the

liquid. The result is a highly efficient transfer of light

energy from the lamp to heat energy in the liquid. Although

quartz is highly useful as a material for making the vessel

42, other vessel materials can be substituted providing that

they are infrared light transparent. The bodies 44 can be made of any inert, opaque,

dielectric material that can absorb infrared energy. They are

suitably made of a dielectric polymer, such as

polytetrafluoroethylene . These bodies 44 absorb the radiant

light from the infrared lamp 46 and become heated, when they

conduct heat to the liquid 43, e.g., water, in which the

bodies 44 are immersed. The bodies 44 are suitably up to about

1/8 inch in size. Small size bodies also act as nucleation

sites for the generation of fine bubbles in the liquid,

helpful in vaporizing the liquid, but averting the formation

of large bubbles that can cause turbulence in the liquid.

Suitably the infrared absorbing bodies are made of

polymeric materials in the form of spheres, but they can be

made in other shapes, such as triangles, cubes and the like.

The reflector 48 can suitably be made of a smooth finish

metal, such as aluminum foil. The reflector 48 is mounted on

the outside of the vessel 42, opposite to the infrared lamp

46. The lamp 46 also heats the backside of the opaque

reflector 48 and reflects and re-directs the light energy back

to the liquid in the vessel .

The generated water or other vapor can be passed into a

line 50, which in turn can be connected to a processing chamber, such as the inlet 20 of the ASP chamber of Fig. 1, alone or together with other inert or reactive gases.

Although the present delivery system has been described

for use with water, other solvents or solutions can be used. If such solvents have a low boiling point, the amount of light generated by the infrared lamp can be adjusted accordingly.

The present water vapor delivery system has been

described as being useful for use with an ASP chamber, but the

present system is applicable for use together with any other processing apparatus requiring delivery of a vapor to the

apparatus .

Although the present invention has been described in

terms of specific embodiments, one skilled in the art can substitute other materials and equipment in order to generate vapor from a liquid and these are meant to be included in the

present invention. The invention is only meant to be limited

by the scope of the appended claims .

Claims

We Claim :

1. A system comprising an infrared lamp mounted adjacent to an

infrared-transparent vessel containing a liquid to be

vaporized and a plurality of opaque dielectric bodies that

absorb infrared energy.

2. A system according to claim 1 wherein a reflector is

mounted on an exterior wall of the vessel opposite to the

lamp.

3. A system according to claim 1 wherein the dielectric bodies

are polymeric .

4. A system according to claim 1 wherein the polymer is

polytetrafluoroethylene .

5. A system according to claim 1 wherein the dielectric bodies

are ceramic .

6. A method of forming a vapor from a liquid comprising

providing an infrared transparent vessel containing the

liquid to be vaporized and a plurality of infrared energy

absorbing bodies, and

exposing the vessel to a source of infrared light.

7. A method according to claim 6 wherein the liquid is water.

8. A method according to claim 6 wherein a reflector of

infrared energy is mounted on a vessel wall opposite to the

infrared light source.

9. A method according to claim 6 wherein the infrared

absorbing bodies are of a ceramic .

10. A method according to claim 6 wherein the infrared

absorbing bodies are of a polymer.