Dopant predeposition from high pressure plasma source

• US 4,382,099 A
• Filed: 10/26/1981
• Issued: 05/03/1983
• Est. Priority Date: 10/26/1981
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Sarma, Kalluri R., Legge, Ronald N.
• Primary Examiner(s): Newsome, John H.
• Application Number:
  US06/314,609
• Time in Patent Office: 554 Days
• Field of Search: 427/34, 427/85
• US Class Current: 438/57
• CPC Class Codes: C23C 16/513 using plasma jets
• CPC Class Codes: C30B 31/02 by contacting with diffusion materials in the solid state
• CPC Class Codes: H01L 21/2254 from or through or into an applied layer, e.g. photoresist, nitrides

Abstract

A method is provided for predepositing dopant material on semiconductor substrates. The semiconductor substrates are positioned within a high pressure plasma reactor apparatus. A high pressure rf plasma is generated in the apparatus at a pressure of about one atmosphere or greater. Dopant materials such as B₂ H₆, PH₃, or AsH₃ are introduced to the plasma and form ionized species of the dopant. The plasma and the ionized species are directed to the surface of the semiconductor substrates whereon a uniform layer of the dopant is deposited.

Claims

1. A method for predepositing dopant material on a semiconductor substrate without codepositing an insulator or semiconductor which comprises the steps of:

providing a high pressure plasma reactor apparatus;

positioning a semiconductor substrate in said apparatus;

generating within said apparatus a high pressure rf plasma at a pressure of about one atmosphere or greater;

introducing dopant material to said plasma to form ionized species of said dopant; and

directing said plasma and said ionized species to impinge upon said semiconductor substrate and to deposit thereon a layer of dopant material only.

2. The method of claim 1 wherein in said step of positioning, said substrate is located to control the temperature of said substrate.

3. A method for forming doped regions in a semiconductor substrate which comprises the steps of:

providing a semiconductor substrate having an exposed surface portion;

positioning said substrate in a high pressure plasma reactor apparatus;

providing a plasma gas;

creating a high pressure rf plasma in said plasma gas at a pressure of about one atmosphere or greater;

introducing a second gas comprising a dopant impurity to said plasma gas;

reacting said second gas in said plasma to form ionized species of said dopant impurity;

directing said plasma toward said exposed surface portion of said substrate to deposit only said dopant impurity thereon; and

heating said substrate to redistribute said dopant impurity in said semiconductor substrate.

4. The method of claim 3 wherein said dopant impurity is selected from the group consisting of B₂ H₆, AsH₃ and PH₃.

5. The method of claim 3 further comprising the step of depositing a layer comprising silicon nitride overlying said dopant impurity.

6. A method for predepositing dopant material on opposed surfaces of a semiconductor substrate which comprises the steps of:

providing a semiconductor substrate having first and second opposed surfaces;

generating a first high pressure rf plasma;

introducing a first dopant material to said first plasma to form a plasma of said first dopant;

directing said plasma of said first dopant to said first opposed surface to deposit a layer of only said first dopant material thereon;

generating a second high pressure rf plasma;

introducing a second dopant material to said second plasma to form a plasma of said second dopant; and

directing said plasma of said second dopant to said second opposed surface to deposit a layer of only said second dopant material thereon.

7. The method of claim 6 wherein said first dopant and said second dopant are of opposite impurity determining type.

8. The method of claim 6 wherein said first and second high frequency plasmas are generated at a pressure of about one atmosphere or greater.

9. The method of claim 6 wherein said substrate is maintained at a temperature of less than about 300°

C. during said steps of directing.

10. A method for making a photovoltaic device which comprises the steps of:

providing a high pressure plasma reactor apparatus;

positioning a substrate of a first conductivity type in said apparatus;

generating in said apparatus a high pressure rf plasma;

introducing to said plasma a dopant of a second conductivity determining type;

directing said plasma and said dopant to a surface of said substrate and forming a layer of only said dopant thereon; and

heating said substrate with said layer thereon to an elevated temperature to form a p-n junction in said substrate.