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Semiconductor Diffusion Source Bar Technique

IP.com Disclosure Number: IPCOM000094416D
Original Publication Date: 1966-Oct-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 1 page(s) / 11K

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VanZant, P: AUTHOR [+2]


This technique utilizes a source bar for diffusing dopants into a semiconductor body.

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This is the abbreviated version, containing approximately 100% of the total text.

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Semiconductor Diffusion Source Bar Technique

This technique utilizes a source bar for diffusing dopants into a semiconductor body.

Conventional diffusion operations usually use boron powders or boron-silicon powders for diffusing boron impurities into a semiconductor body. This source for a boron type diffusion utilizes a slug or bar of silicon having an opening, cut, or depression preferably etched in the bar's center. Boron powders are placed in the depression together with B(2)O(3). The use of the bar does not resulting the usual surface damage experienced with elemental boron. The B(2)O(3) forms a glassy layer at room temperature over the powdered boron and prevents the boron from flying around during capsule loading and unloading operations. The use of a pure boron source allows a maximum solid solubility diffusion operation which is both consistent and controllable. The bars are made by the following procedure: 1. Etch a 3/8'' dia. x 3/16'' deep depression in a 1-1/4'' dia. x 3/8'' slug of 1 ohm-cm or higher silicon. 2. Etch the bar to make a depression. 3. Weigh out 0.255 grams of elemental boron powder, 100 mesh particles, and place in depression. 4. Mix the boron with 0.225 grams of B(2)O(3). The B(2)O(3) should be below the bar surface. 5. Place the boron-B(2)O(3) mixture into the bar depression. 6. Place the loaded bar in an etched, prebaked capsule and evacuate to 5 x 10/-5/ torr. 7. Bake out under vacuum at 700 degrees C for 90 minutes.