Abstract of the Disclosure

A method for making an integrated circuit transistor. A buried collector layer is produced by epitaxial growth. The base and emitter are diffused into the grown layer. The collector uses impurities with tow different diffusion constants (arsenic and phosphorus). This produces a U-shaped buried collector.

• Figure 1 illustrates a plan view of a semiconductor chip after the first step of an embodiment of the invention.
• Figure 2 is a cross-section view taken along lines 2-2 of Figure 1.
• Figure 3 illustrates the chip shown in Figure 2 during the second step of an embodiment of the invention.
• Figure 4 illustrates the chip shown in Figure 2 after the second step of an embodiment of the invention.
• Figure 5 illustrates the chip shown in Figure 2 after the third step of an embodiment of the invention.
• Figure 6 illustrates the chip shown in Figure 2 after the fourth step of an embodiment of the invention.

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3,340,598  09/1967  Hatcher