US 3887392 A
Disclosed is a material treatment method including the steps of impregnating a porous carrier sheet with a treating material, positioning the sheet in contact with a material substrate, and inducing transfer of the treating material by applying microwave energy to the impregnated sheet. Deposition, cleansing and cooking operations are possible with the method described.
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Description (OCR text may contain errors)
atent 1 Unite @QMQS Tang [451 June 3,1975
[ MATERIAL TREATMENT METHOD  Assignee: General Diode Corporation,
 Filed: Nov. 23, 1973  Appl. No.: 418,369
 U.S. Cl 134/1; 134/40  Int. Cl B08b 7/00  Field of Search 156/230; 426/237, 246, 426/241, 289, 272, 273, 289, 502, 383, 250; 134/1, 40
 References Cited UNITED STATES PATENTS 2,878,188 3/1959 Ca1lahan.... 134/40 2,949,121 8/1960 Kearney 134/1 3,121,650 2/1904 Meisner 156/240 3,257,021 6/1966 Brockett 156/240 3,434,902 3/1969 Bliss 156/230 3,445,310 5/1969 Danielson 156/230 3,447,989 6/1969 Yamashita 156/383 3,454,458 7/1969 Borregard 156/230 3,459,626 8/1969 3,462,329 8/1969 3,551,241 12/1970 3,554,832 l/197l 3,600,256 8/1971 Tosaka 156/230 Primary ExaminerSamih N. Zaharna Assistant Examiner-Ernest G. Therkorn Attorney, Agent, or Firm.lohn E. Toupal  ABSTRACT Disclosed is a material treatment method including the steps of impregnating a porous carrier sheet with a treating material, positioning the sheet in contact with a material substrate, and inducing transfer of the treating material by applying microwave energy to the impregnated sheet. Deposition,cleansing and cooking operations are possible with the method described.
3 Claims, No Drawings MATERIAL TREATMENT METHOD BACKGROUND OF THE INVENTION This invention relates to a method for transferring materials and, more particularly, to a method for transferring materials under the influence of microwave energy.
In many processes a material substrate is coated with a treating substance and then heat is applied to induce some interaction between the substrate and the substance. Often, the coating of the substrate with the treating substance is a time consuming manual operation. This operation could be simplified if the treating substance could be applied via a preimpregnated sheet material. However, the requirement for subsequent ap plication of heat generally renders the use of heat sensitive sheet materials impractical.
It is an object of this invention, therefore, to provide a simplified method of first coating a material substrate with a treating substance and then inducing transfer thereof by the application of heat.
SUMMARY OF THE INVENTION This invention is characterized by a material treatment method involving the transfer of a treating material. A material to undergo a controlled transfer is impregnated in a carrier vehicle which is brought in contact with a substrate. Microwave energy is then applied to the carrier to induce heating and resultant transfer of the treating material. Preferably, the treating material includes an organic substance that will generate heat as a result of the application of the microwave energy. Different processes are possible with the subject method depending upon the particular choice of treating material and substrate. For example, a cleansing operation can be performed on a material substrate by covering the substrate with a carrier impregnated with a suitable solvent and applying microwave energy vaporize the solvent and carry off the contaminants from the surface of the substrate. Similarly deposition processes can be performed by covering a substrate with a carrier impregnated with a deposition compound and then applying microwave energy to heat the compound and induce deposition thereof on the substrate. Still other features of the present invention will become more apparent upon a perusal of the following description which includes several preferred material treatment examples of the subject invention.
DESCRIPTION OF THE PREFERRED METHODS Example 1 Crystalline substrate materials such as, for example, silicon wafers utilized for manufacturing semiconductors, are often contaminated with grease, oils or dirt during the manufacturing process. The subject method can be utilized to clean the wafers as follows: A cloth or porous paper sheet is first soaked in a solvent treating material such as alcohol. The solvent impregnated sheet is then placed on an array of the wafers either then positioned or moved thereafter into a microwave oven. In response to the microwave energy, the alcohol which has mixed with the oils and dirt will vaporize and carry off the contaminants.
Example 2 Considering agent hard surface materials such as the semiconductor wafers described above, coating operations also are possible. For example, a primary treating material oxide such as boric acid or phosphorus pentoxide can be mixed with an organic binder such as a celluloid. The mixture is then impregnated into a porous sheet which is then placed on the wafers. Again the wafer can be covered after being positioned in a microwave oven or can be placed therein subsequently, for example, by conveyor belt. When microwave energy is applied the binder is heated burned inducing the release of oxygen from the treating material. Depending upon which of the above materials was employed either boron or phosphorus will remain coated on the silicon wafers.
The method given in examples 1 and 2 above can be used in sequence very effectively during the manufacture of semiconductor materials or other materials requiring initial cleaning followed by a coating process.
Example 3 Household uses for the subject method also exist. For example, an absorbent sheet of material such as paper or synthetic cloth, can be impregnated with edible oil, such as corn, olive or peanut oil, and placed on a substrate of food to be cooked. For example, the impregnated sheet can be placed on a cut of meat to be cooked in a microwave oven. Moisture that would normally be driven out of the meat is combined with the oil and thus the transfer of moisture from the meat is controlled. Furthermore, the heating of the oil in the paper facilitates browning of the meat. Some meats, containing little oil tend to steam and turn gray rather than brown when cooked in microwave ovens. Utilization of the subject method prevents such steaming. Furthermore, mositure loss is prevented thereby producing a more palatable final product.
According to a further feature of this method, certain procedures generally used while cooking can be eliminated. For example, seasoning steps can be eliminated by adding suitable food seasonings salt, pepper, etc., to the material impregnated in the carrier sheet. The added seasoning will then be transferred to the product along with the cooking oil released by the microwave heating.
An added benefit derived from the use of the method described under example 3 results from the retention of moisture in the meat. It has been found that moisture tends to carry harmful radiation out of exhaust passages from the microwave cooking apparatus. Thus the potentially dangerous release of microwave energy and the inefficiency caused by the release of such energy is prevented.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings. For example, it will be readily apparent that the treatment method disclosed can be used in processes other than those specifically described. It is to be understood, therefore, that the invention can be practiced otherwise than as specifically described.
What is claimed is:
l. A method of cleaning a material substrate, having impurities which are capable of being dissolved in and co-vaporized with solvent on the application thereto of microwave energy, the method consisting essentially of: providing a porous carrier sheet; impregnating said carrier sheet with said solvent; positioning said impregnated carrier sheet in contact with said material substrate; applying microwave energy to said impregnated carrier sheet so as to generate heat therein and thereby as semiconductors vaporize lmpumles and Sam Solvent and remove 3. A device according to claim 1 wherein said solvent the same from said material substrate.
2. A device according to claim 1 wherein said substrate material comprises silicon wafer material for use 5 comprises alcohol.