System for Self-Aligned Contacts

A method of forming self-aligned contacts, comprising:

• electroplating a first metal contact onto a Group III-V semiconductor substrate, said first metal contact having a greater height than width and having a straight sidewall profile;
• etching back said semiconductor substrate down to a base layer to expose an emitter semiconductor layer under said first metal contact;
• conformally depositing a dielectric layer on a vertical side of said first metal contact, a vertical side of said emitter semiconductor layer and on said base layer;
• anisotropically etching said dielectric layer off of said semiconductor substrate to form a dielectric sidewall spacer on said vertical side of said first metal contact;
• depositing a second metal contact immediately adjacent said dielectric sidewall spacer;
• depositing a dielectric blanket layer on said dielectric sidewall spacer prior to said depositing a second metal contact;
• depositing a planarizing layer on said dielectric blanket layer;
• and
• selectively etching said dielectric blanket layer to form a second contact opening to receive said second metal contact;
• wherein the thickness of said dielectric blanket layer determines the width of the second metal contact, with the second contact having inner and outer edges that are self aligned with the first contact.