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957293 ALS

February 1, 1995

CLA-2 CO:R:C:F 957293 ALS


TARIFF NO.: 3818.00.0010

Mr. Richard C. King
Attorney at Law
Fitch, King and Caffentzis
116 John Street
New York, NY 10038

RE: Carbon Doped Gallium Arsenide Wafers

Dear Mr. King:

This is in reference to your inquiry regarding the subject wafers on behalf of Marubeni America, Inc.


The subject merchandise consists of highly-resistive carbon- doped gallium arsenide (GaAs) wafers. The wafers are produced from compound crystal ingots grown by the Liquid Encapsulated Czochralski (LEC) method. The carbon doping concentration is controlled by degassing impurities present in the raw material (including contaminated carbon), and then introducing controlled carbon concentration through the addition of purified carbon monoxide gas (CO), as the crystal is pulled. The purpose of this doping procedure is to alter the electrical characteristics of the wafers, their conductivity and their resistivity. They are used in electronics.


What is the classification of the subject wafers?


Classification of merchandise under the Harmonized Tariff Schedule of the United States Annotated (HTSUSA) is governed by - 2 -
the General Rules of Interpretation (GRI's) taken in order. GRI 1 provides that the classification is determined first in accordance with the terms of the headings and any relative section and chapter notes. If GRI 1 fails to classify the goods and if the headings and legal notes do no otherwise require, the remaining GRI's are applied, taken in order.

Counsel has suggested that the subject wafers are properly classified in subheading 3818.00.0010, HTSUSA, as gallium arsenide wafers, doped. Customs, however, has historically classified such wafers under subheading 2851.00.0000, HTSUSA, as other products of the chemical industry, for wafers under 2.5 grams, or under subheading 3823.90.1900, HTSUSA, for wafers not less that 2.5 grams. Our rational for doing so has been that all gallium wafers contain carbon and that such carbon is not in the proportion required in Explanatory Note 38.18(2) to the Harmonized System (EN), which represents the view of the international classification experts.

Counsel notes that carbon doping concentration is controlled by degassing impurities present in the raw material (including contaminated carbon), and then introducing controlled carbon concentration though the addition of purified carbon monoxide gas (CO), as the crystal is pulled. The process is noted to be analogous to the process used in the production of silicon doped boat grown GaAs wafers. Counsel has submitted SEMI M9-90, Specifications for Polished Monocrystalline Gallium Arsenide Slices, of the Semiconductor Equipment and Materials International (SEMI) and draft document number 2048 in support of its position.

In analyzing these documents we noted that they referred to carbon as a dopant. We, however, found no basis presented therein for such conclusion. That document did not seem to confirm that carbon was added to gallium arsenide wafers in order to give the material specific electrical properties, i.e., increased its resistivity. However, three important technical sources, ASTM Handbook of Standards, the Encyclopedia of Chemical Technology, Kirk, Othmer, and the Modern Dictionary of Electronics, 6th, 1990, do not refer to carbon as a dopant. In light of this and since the addition of carbon to the gallium arsenide wafers only increases the carbon in the crystals but does not introduce the carbon, a question has existed as to whether it could be concluded that the carbon was introduced to significantly alter the crystals conductivity. Accordingly, we had tentatively concluded that carbon was not an industry recognized dopant and that the subject gallium arsenide wafers were not doped. - 3 -

Subsequent thereto counsel submitted certain previously unavailable technical data on Hitachi III-V Semiconductors it obtained from the manufacturer of the gallium arsenide wafers (Hitachi Cable, Ltd.). That technical data confirms in its specification of AU grade carbon-doped wafers that the wafers, which are available in several sizes, are carbon-doped and that the resistivity of each different type of wafer is dependant upon the concentration of carbon. The data confirms that such doping is accomplished by special carbon doping manufacturing equipment which adds carbon during the crystal seeding and growth cycles. Accordingly, we have concluded that the gallium arsenide wafers under consideration are doped for use in electronics.


Carbon-doped gallium arsenide wafers in which carbon is added during the crystal seeding and growth cycles to control the conductivity or resistivity of the wafers, are classifiable in subheading 3818.00.0010, HTSUSA, Gallium arsenide wafers, doped, for use in electronics. Such wafers are subject to a free rate of duty.


John Durant, Director
Commercial Rulings Division

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