Processes for treating electronic components

Details Processes for treating electronic components Processes for treating electronic components

2001-03-13

2002-12-10

Gulakowski, Randy (Department: 1746)

Cleaning and liquid contact with solids

Processes

Using sequentially applied treating agents

C134S030000, C134S031000, C134S002000, C134S003000

Reexamination Certificate

active

06491763

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to processes and apparatus for treating electronic components and, in particular, to processes and apparatus for treating semiconductor wafers with a combination of a heated solvent and an ozonated process fluid to remove or strip bulk photoresist.
BACKGROUND OF THE INVENTION
Wet processing of electronic components, such as semiconductor wafers, flat panels, and other electronic component precursors is used extensively during the manufacture of integrated circuits. Semiconductor fabrication is described generally, for example, in P. Gise et al., Semiconductor and Integrated Circuit Fabrication Techniques (Reston Publishing Co. Reston, Va. 1979), the disclosure of which is herein incorporated by reference in its entirety.
Preferably, wet processing is carried out to prepare the electronic components for processing steps such as diffusion, ion implantation, epitaxial growth, chemical vapor deposition, hemispherical silicon grain growth, or combinations thereof. During wet processing, the electronic components are contacted with a series of processing solutions. The processing solutions may be used, for example, to etch, remove photoresist, clean, grow an oxide layer, or rinse the electronic components. See, e.g., U.S. Pat. Nos. 4,577,650; 4,740,249; 4,738,272; 4,856,544; 4,633,893; 4,778,532; 4,917,123; and EP 0 233 184, assigned to a common assignee, and Burkman et al.,
Wet Chemical Processes
-
Aqueous Cleaning Processes,
pg. 111-151 in
Handbook of Semiconductor Wafer Cleaning Technology
(edited by Werner Kern, Published by Noyes Publication Parkridge, New Jersey 1993), the disclosures of which are herein incorporated by reference in their entirety.
There are various types of systems available for wet processing. For example, the electronic components may be processed in a single vessel system closed to the environment (such as an Omni system employing Full-Flow™ technology supplied by Mattson Technology, Inc.), a single vessel system open to the environment, or a muliple open bath system (e.g., wet bench) having a plurality of baths open to the atmosphere.
Following processing, the electronic components are typically dried. Drying of the semiconductor substrates can be done using various methods, with the goal being to ensure that there is no contamination created during the drying process. Methods of drying include evaporation, centrifugal force in a spin-rinser-dryer, steam or chemical drying of wafers, including the methods and apparatus disclosed in, for example, U.S. Pat. No. 4,911,761.
An important consideration for an effective wet processing method is that the electronic component produced by the process be ultraclean (i.e., with minimum particle contamination and minimum chemical residue). An ultraclean electronic component is preferably free of particles, metallic contaminants, organic contaminants, and native oxides; has a smooth surface; and has a hydrogen-terminated surface. Although wet processing methods have been developed to provide relatively clean electronic components, there is always a need for improvement because of the intricacies associated with technological advances in the semiconductor industry. One of the most challenging problems of attaining ultraclean products is the removal of photoresist.
The use of ozone for removing organic material, such as photoresist, from semiconductor wafers has been investigated. For example, U.S. Pat. No. 5,464,480 issued to Matthews (hereinafter “Matthews”), describes a process in which semiconductor wafers are contacted with a solution of ozone and water at a temperature of about 1° C. to about 15° C. Matthews discloses, for example, placing the semiconductor wafers into a tank containing deionized water, diffusing ozone into the deionized water for a time sufficient to oxidize the organic materials from the wafers, while maintaining the temperature of the water at between about 1° C. to about 15° C., and then rinsing the wafers with deionized (DI) water. Matthews further discloses exposing the wafers to ultraviolet light during the process.
Various other methods have been investigated using ozone in conjunction with water to strip organic materials from the surface of semiconductor wafers or to rinse wafers after chemical processing. For example, in one such method, ozone gas is generated in an ozone generator and fed to an ozonator where the ozone gas is mixed with DI water. The ozone gas is also simultaneously fed to the bottom of the process vessel via a specially designed device that provides a uniform stream of gaseous ozone into the bath. Matthews et al.,
Mat. Res. Soc. Symp. Proc.,
1997, 477, 173-78. See also 1997
Joint Int'l Mtg. of Electro. Chem. Soc'y and Int'l Soc'y. of Electro., Abstract
1886, p. 2169 submitted by Kenens et al.; Id. at Abstract 1887, p. 2170, submitted by Wolke et al.; Id. at Abstract 1892, p. 2176, submitted by Fukazawa et al.; Id. at Abstract 1934, p. 2236, submitted by Kashkoush et al.; Id. at Abstract 1890, p. 2173, submitted by Li et al.; Id. at Abstract 1891, p. 2174, submitted by Joo et al.; Ultra Clean Processing of Silicon Surfaces UCPSS 1996, Kenens et al.,
Removal of Organic Contamination From Silicon Surfaces,
p. 107-110.
In another method, the use of ozone-injected ultrapure water (ozone concentration of about 1-2 ppm) is applied to the RCA or other similar cleaning methods. The ozonated water is used to remove organic impurities. The wafers are then treated with NH
4
OH and H
2
O
2
to remove metallic ion contaminants, followed by a treatment with HF and H
2
O
2
to remove native oxide and metal, and to improve surface smoothness. The wafers are then rinsed with DI water. The ozone gas is generated by electrolyzing ultra pure water. The generated ozone gas is then dissolved in ultrapure water through a membrane. Ohmi et al.,
J. Electrochem. Soc'y
140, 1993, 804-10.
Another method uses a moist ozone gas phase. In this method, a quartz container is filled with a small amount of liquid, sufficient to immerse an O
3
diffuser. The liquid is DI water spiked with additives such as hydrogen peroxide or acetic acid, if appropriate. A lid is placed on the container and the liquid is heated to 80° C. Wafers are placed directly above the liquid interface (i.e., the wafers are not immersed in the liquid). Heating of the liquid in a sealed container and continuous O
3
bubbling through the liquid exposes the wafers to a moist ambient O
3
environment. De Gendt et al.,
Symp. VLSI Tech. Dig. Tech. Papers,
1998, 168-69. The De Gendt paper further describes a method whereby a quartz tank is filled with 7 liters of liquid, an ozone diffuser is located at the bottom of the tank, and the liquid is heated. The wafers are positioned directly above the ozone diffuser and immersed in the liquid such that O
2
/O
3
bubbles contact the wafer surfaces. The De Gendt paper also reports that OH radical scavengers such as acetic acid can enhance process efficiency.
In another method, photoresist removal is carried out in a gas phase reactor at a temperature of between about 200-300° C. In certain instances, additives such as N
2
O gas are mixed with the ozone gas. See Olness et al., Mat. Res. Soc'y. Symp., 135, 1993, 261-66.
Spin cleaning techniques using ozonated water have also been investigated. See, e.g., Cleaning Technology In Semiconductor Device Manufacturing Symposium, Yonekawa et al.,
Contamination Removal By Wafer Spin Cleaning Process With Advanced Chemical Distribution System,
94-7, 94-101; 1997
Joint Int's Mtg. of Electro. Chem. Soc'y and Int'l Soc'y. of Elctro., Abstract
1888, p. 2171 submitted by Osaka et al.
The use of ozone with cleaning solutions has also been investigated. One such method uses a wafer cleaning sequence with a single-wafer spin using ozonated water and dilute HF to remove contaminants such as particles, metallics, and organics from the wafer surfaces. The method consists of pouring ozonated water on a wafer surface for 10 seconds, followed by pouring

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