| 摘要 |
<p>930,487. Semi-conductor devices. PACIFIC SEMICONDUCTORS Inc. April 6, 1961 [Oct. 13, 1960], No. 12396/60. Class 37. A semi-conductor crystal has an impurity diffused into it from an organic compound including the impurity. The compound is one which is capable of releasing the impurity at a temperature below the melting-point of the semi-conductor body. The invention is described with reference to introducing boron into silicon wafers and the substance used is trymethoxyboroxine to introduce boron into the crystal and trimethoxysilane which is used as a solvent for the trimethoxyboroxine although the solvent may be entirely omitted. In a first method the silicon plates a (Fig. 3) are coated on one surface with the liquid 12 and then placed in a stack with the coated faces adjacent each other in a quartz tube open to the atmosphere. The whole is heated to a temperature between 600‹ and 1380‹ C. and, if the highest temperature is used, a diffusion time of 8 to 76 hours is necessary. The Specification states that a relatively thick diffused layer is produced on the face adjacent the polymer and a relatively thin one on the opposite face. Prior to stacking the plates may be heated to from 50‹ to 200‹ C. to render the coating relatively solid. The glassy substance which the polymer becomes may be removed together with the thicker diffusion layer and the other layer used. The polymer is said to give up boron upon oxidation in the presence of water and heat. If the silane is an independent silicon source it will prevent pitting of the silicon by B 2 O 3 which is evolved during the diffusion run. In a further embodiment the plates are not coated but are stacked in a quartz tube furnace the inside of which is coated with the impurity source. Analogous boroxine compounds such as alkyl and anyl boroxines may be used provided they are liquid at room temperature, if necessary when dissolved in a suitable solvent.</p> |
