Method for etching heterojunction bipolar transistor base substrate by employing single-layer mask

Abstract

The invention discloses a method for etching a heterojunction bipolar transistor base substrate by employing a single-layer mask. The method comprises the steps of S1, performing wet etching by photoetching and H3PO4 corrosion; S2, completing SiN deposition; S3, completing a BP pattern photoetching by employing a BP photomask to form a BP mask; S4, performing dry etching on a SiN thin film with SF6 and O2; S5, corroding an InGaP layer below the SiN thin film with an HCL solution; S6, performing wet etching on a GaAs layer below the InGaP layer with a mixed solution of H3PO4 and H2O2; S7, completing wet etching on the InGaP layer below the SiN thin film; S8, performing dry etching on the SiN thin film with the SF6 and the O2; and S9, performing wet removal on BP photoresist by employing anNMP solution. A side wall etching process for twice is added on the basis of original equipment, thus, the photomask process can be saved, and the method is simple to implement and is low in cost.

Description

technical field [0001] The invention relates to the field of semiconductor processing, in particular to a method for etching a base base of a heterojunction bipolar transistor using a single-layer photomask. Background technique [0002] The base pedestal is the slope between the collector and the base in the heterojunction bipolar transistor device, and its electrical influence is BVceo and BVcbo. The prior art uses a double-layer photomask (BR, BP Mask) etching process, which not only uses one more photomask, but also requires removal of photoresist and surface treatment, which wastes cost. However, in the single-layer photomask process used in the prior art, when phosphoric acid and hydrogen peroxide are mixed to etch the main GaAs, the GaAs under the InGaP will be side-etched, causing the BP InGaP and Nitride to be exposed, resulting in the problem that the subsequent evaporated gold line is broken on the Base Pedestal slope. . Contents of the invention [0003] The ...

AI Technical Summary

Problems solved by technology

The existing technology uses a double-layer photomask (BR, BP Mask) etching process, which not only uses one more photomask in the yellow light production process, but also needs to remove photoresist and surface treatment, which wastes cost

However, in the single-layer photomask process used in the prior art, when phosphoric acid and hydrogen peroxide are mixed to etch the main GaAs, the GaAs below the InGaP will be etched sideways, causing the BP InGaP and Nitride to be exposed, resulting in the problem that the subsequent evaporated gold line is broken on the Base Pedestal slope.

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