Plasma-assisted CVD of carbonaceous films by using a bias voltage

• US 5,230,931 A
• Filed: 07/01/1991
• Issued: 07/27/1993
• Est. Priority Date: 08/10/1987
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Hayashi, Shigenori
• Primary Examiner(s): KING, ROY V
• Application Number:
  US07/725,896
• Time in Patent Office: 757 Days
• Field of Search: 427/39, 427/38, 427/45.1, 427/47, 427/255.2, 427/122, 427/569, 427/575, 427/577, 427/571, 423/446, 118/723, 118/728
• US Class Current: 427/569
• CPC Class Codes: C23C 16/26 Deposition of carbon only

Abstract

Diamond films or I-Carbon films can be formed on a surface of an object by virtue of plasma-assisted chemical vapor deposition. The hardness of the films can be enhanced by applying a bias voltage to the object during deposition.

Claims

1. A method of depositing a material constituting mainly of carbon comprising the steps of:

placing an object to be coated in the reaction space of a reaction chamber;

introducing a reactive gas comprising carbon into said reaction space;

inputting electric energy to said reaction space by means of a pair of electrodes in order to provide plasma and decompose said reactive gas and deposit said material on the surface of said object where said object is placed on a holder spaced from each of said pair of electrodes, wherein a bias voltage is applied to said object for enhancing the hardness of the deposited material voltage.

2. The method of claim 1 wherein said electric energy is supplied from the respective ends of a secondary coil of a transformer, where the midpoint of the secondary coil is grounded.

3. The method of claim 2 wherein the frequency of said electric energy is 1 MHz to 5 GHz.

4. The method of claim 1 wherein said bias voltage is an AC bias voltage.

5. The method of claim 4 wherein the frequency of said AC bias voltage is 1 KHz to 500 KHz.

6. The method of claim 2 where said bias voltage is applied to said object from a voltage source connected between the grounded midpoint of the secondary coil and the object to be coated.

7. A method of depositing a carbonaceous material comprising the steps of:

placing an object to be coated between a pair of electrodes in a reaction chamber;

introducing a reactive gas comprising carbon into said reaction chamber;

inputting a first voltage to said pair of electrodes in order to convert said reactive gas to plasma; and

depositing said carbonaceous material on said object,

wherein said object is placed on a substrate holder spaced apart from said pair of electrodes and wherein said substrate holder is supplied with a second voltage in order to induce a bias voltage on said object for enhancing the hardness of the deposited carbonaceous material.

8. The method of claim 7, wherein said first voltage is a high frequency voltage.

9. The method of claim 8, wherein a frequency of said second voltage is lower than that of said first voltage.