Growth of polycrystalline semiconductor film with intermetallic nucleating layer

• US 4,132,571 A
• Filed: 02/03/1977
• Issued: 01/02/1979
• Est. Priority Date: 02/03/1977
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Rosenberg, Robert, DiStefano, Thomas H., Cuomo, Jerome J.
• Primary Examiner(s): Bernstein, Hiram H.
• Application Number:
  US05/765,497
• Time in Patent Office: 698 Days
• Field of Search: 156/609, 148/174, 148/175, 148/1.5, 148/177
• US Class Current: 438/488
• CPC Class Codes: C23C 14/02 Pretreatment of the material to be coated C23C14/04 takes precedence
• CPC Class Codes: C23C 16/003 Coating on a liquid substrate
• CPC Class Codes: C30B 11/12 Vaporous components, e.g. vapour-liquid-solid-growth
• CPC Class Codes: C30B 23/02 Epitaxial-layer growth
• CPC Class Codes: C30B 25/18 characterised by the substrate
• CPC Class Codes: C30B 29/06 Silicon
• CPC Class Codes: Y10S 148/061 Gettering-armorphous layers
• CPC Class Codes: Y10S 148/154 Solid phase epitaxy

Abstract

A method is disclosed for fabricating a thin elemental semiconductor, e.g., Si or Ge, film with columnar grains in a filamentary structure, by the use of an intermetallic compound incorporating the elemental semiconductor to form a nucleating layer for the growth of the semiconducting film. The semiconductor is grown from vapor phase by the technique of either vacuum evaporation or chemical vapor deposition, e.g., by decomposition of SiH₄. The semiconductor e.g., Si, is initially deposited onto a thin film of a specific metal, e.g., Pt or Ni, on any inert substrate, e.g., SiO₂ or Al₂ O₃, which is held at a temperature, e.g., 900° C, above the eutectic point, i.e., 830° C, of an intermetallic compound and the metallic film, and below the eutectic point, i.e., 979° C, of another intermetallic compound and the semiconductor.

Deposition of the semiconductor onto the metallic film produces a layer of liquid comprising the semiconductor and metal, which increases in thickness until the metallic layer is completely consumed. Additional deposition of the semiconductor produces a supersaturated liquid from which large crystallites of the intermetallic precipitate. With increasing deposition of semiconductor, the crystallites of intermetallic material continue to grow until they consume all of the metal in the liquid, at which point no liquid remains. Continuing deposition of semiconductor material results in the growth of filamentary crystallites of the semiconductor out of the intermetallic surface. The result is a columnar film of the semiconductor with a filamentary structure originating from the crystallites of intermetallic nucleating material.

Claims

1. Method for the controlled growth of a polycrystalline semiconductor material with course columnar grains comprising the steps of:

providing a metallic material, which is supported by a substrate which is unreactive with said metallic material,

said metallic material being capable of forming a first eutectic or peritectic composition at a first temperature with an intermetallic compound of said semiconductor material and said metallic material,

said metallic material being capable of forming an intermetallic compound richer in said semiconductor material than said first eutectic or peritectic composition,

said latter intermetallic compound being capable of forming a second eutectic or peritectic composition at a second temperature, which is higher than said first temperature, with said semiconductor, and

said metallic material and said semiconductor material being capable of forming a liquid in a range of temperatures between said first and second temperatures;

heating said metallic material to a temperature within said range of temperatures;

contacting said heated metallic material with a vapor comprising said first semiconductor material to form a first liquid which is unsaturated with respect to said semiconductor material;

continuing said contacting said first liquid for a time sufficient to supersaturate said first liquid with respect to said semiconductor material to form a supersaturated liquid which initiates precipitation of at least one intermetallic compound of said semiconductor material and said metallic material from said supersaturated liquid onto said substrate forming said nucleating layer;

continuing said precipitation of said nucleating layer from said supersaturated liquid until all said supersaturated liquid has been exhausted; and

continuing to hold said nucleating layer in the presence of said vapor so that said polycrystalline semiconductor material is deposited on said nucleating layer,

wherein said precipitate which forms an intermediate layer between said substrate and said polycrystalline semiconductor material, creates a Schottky-barrier with said semiconductor material.

2. Method as set forth in claim 1 wherein said polycrystalline semiconductor material is Si and said metallic material is selected from the group consisting of Pt, Ni, Pd and Co and further wherein said intermetallic compound which precipitates onto said substrate is selected from the group consisting of the following, within the related identified temperature ranges:

Pt--Si (830°

C. <

T <

979°

C.), Ni--Si (966°

C. <

T <

993°

C.), Pd--Si (720°

C. <

T <

850°

C.), and Co--Si (1195°

C. <

T <

1258°

C.).

3. Method as set forth in claim 2 wherein said vapor is maintained at a pressure level so as to assure the Si grains were 5-10 microns.

4. Method as set forth in claim 3 wherein said vapor results from the deposition of silane gas wherein said pressure is about 4 torr.