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US4704301A Expired / Lapsed US ⏱️ 0.0 years remaining

Method of making low resistance contacts

Assignee: International Business Machines Corp
•
Filing: 1986-01-16
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Granted: 1987-11-03
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Expires: 2006-01-16
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Abstract

Abstract The invention relates to a method of making low resistance contacts between first and second metallization levels in integrated semiconductor circuits. In accordance with the invention, the semiconductor substrates to be cleaned are arranged on a substrate holder in a vacuum chamber. There, a gas plasma is generated by means of a getter electrode made of a material which has a high affinity for oxygen or oxygen containing compounds. This improves the vacuum by reducing the steam partial pressure. The actual cleaning of the exposed surfaces of the semiconductor substrate is effected subsequently by means of cathode sputtering through applying a radio frequency voltage to the substrate holder. By sputtering material from the surface of the getter electrode prior to cathode sputtering of the semiconductor substrate surface, the time for cleaning the semiconductor substrates can be considerably reduced so that it is also possible to clean substrates with masks of temperature-sensitive photoresists by means of cathode sputtering. The invention also comprises a device for carrying out said method.

Inventors

  • 👤 Hans J. Bauer
  • 👤 Marianne B. Froehlich

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-31 19:08
CPC Classifications
H; H10; H10P; H10P70/00; H10P70/20; H10P70/23; H10P70/234; C; C23; C23C; C23C14/00; C23C14/02; C23C14/021; C23C14/022; H01; H01J; H01J37/00; H01J37/02; H01J37/18; H01J37/32; H01J37/32431; H10D; H10D64/00; H10D64/01; H10D64/011; H10D64/0111; Y; Y10; Y10S; Y10S438/00; Y10S438/906; Y10S438/909

Claims Analysis

Total Claims: 33
Claim 1
Independent Claim 160 words
A method of forming contaminant free surfaces on metallized areas of a substrate comprising the steps of: placing one or more substrates having exposed metallized areas and photoresist thereon into a high vacuum manufacturing chamber having resilient seals and a getter electrode having a high affinity for oxygen mounted therein; positioning said substrates so that they are in close proximity to said getter electrode but electrically isolated therefrom and so that the exposed areas of said metallized areas of said substrates are substantially surrounded by a surface of said electrode; evacuating said high vacuum manufacturing chamber, introducing a noble gas into said high vacuum manufacturing chamber, producing a gas plasma at said getter electrode, reducing the partial pressures of oxygen containing gases in said high vacuum manufacturing chamber; subsequently and independently to producing said gas plasma, applying a radio frequency voltage to said substrates, causing cathode sputtering of said substrates, thereby cleaning exposed surfaces on metallized areas of said substrates.
Claim 2
Independent Claim 160 words
A method of forming contaminant free surfaces on metallized areas of a substrate comprising the steps of: placing one or more substrates having exposed metallized areas and photoresist thereon into a high vacuum manufacturing chamber having resilient seals and a getter electrode having a high affinity for oxygen mounted therein; positioning said substrates so that they are in close proximity to said getter electrode but electrically isolated therefrom and so that the exposed areas of said metallized areas of said substrates are substantially surrounded by a surface of said electrode; evacuating said high vacuum manufacturing chamber, introducing a noble gas into said high vacuum manufacturing chamber, producing a gas plasma at said getter electrode, reducing the partial pressures of oxygen containing gases in said high vacuum manufacturing chamber; subsequently and independently to producing said gas plasma, applying a radio frequency voltage to said substrates, causing cathode sputtering of said substrates, thereby cleaning exposed surfaces on metallized areas of said substrates.
Claim 3
Dependent Claim 42 words
The method of claim 1 wherein said vacuum chamber is evacuated down to a pressure of less than approximately 1.33×10 -6 milliber and said noble gas is introduced at a pressure in the range of approximately 1.33×10 -4 to 1.33×10 -1 millibar.
Claim 4
Dependent Claim 20 words
The method of claim 1 wherein a direct voltage is applied to the getter electrode to create a gas plasma.
Claim 5
Dependent Claim 21 words
The method of claim 1 wherein a radio frequency voltage is applied to the getter electrode to create a gas plasma.
Claim 6
Dependent Claim 24 words
The method of claim 1, 2, 3 or 4 wherein the gas plasma is generated for a period of approximately 7 to 20 minutes.
Claim 7
Dependent Claim 24 words
The method of claim 5 wherein said high frequency voltage is applied to said substrates for a period of approximately 0.5 to 5 minutes.
Claim 8
Dependent Claim 26 words
The method of claim 6 wherein the energy density implemented during said cathode sputtering is in the range of approximately 0.1 to 1 watts/cm 2 .
Claim 9
Dependent Claim 31 words
The method of claim 1, 2 or 3 further comprising the step of vapor depositing the next metallization level subsequent to said cleaning step while said vacuum chamber is still evacuated.
Claim 10
Dependent Claim 28 words
The method of claim 6 further comprising the step of vapor depositing the next metallization level subsequent to said cleaning step while said vacuum chamber is still evacuated.
Claim 11
Dependent Claim 158 words
A sputter cleaning apparatus for forming contaminate free surface on metallized areas of a substrate comprising: a high vacuum manufacturing chamber having resilient seals and means for evacuating said chamber; a substrate holder for receiving and holding substrates, said substrate holder being suitably connected to the inside of said chamber; a getter electrode and means for applying a voltage thereto for generating a gas plasma, said getter electrode having a high affinity for oxygen and being suitably arranged on the inside of said high vacuum manufacturing chamber so that the exposed areas of said metallized areas of said substrates are substantially surrounded by a surface of said getter electrode; said substrate holder and said getter electrode being electrically isolated from each other means for applying a radio frequency voltage to said substrates independently of said means to apply a voltage to said getter electrode, said radio frequency voltage causing cathode sputtering of said metallized areas of said substrates.
Claim 12
Dependent Claim 158 words
A sputter cleaning apparatus for forming contaminate free surface on metallized areas of a substrate comprising: a high vacuum manufacturing chamber having resilient seals and means for evacuating said chamber; a substrate holder for receiving and holding substrates, said substrate holder being suitably connected to the inside of said chamber; a getter electrode and means for applying a voltage thereto for generating a gas plasma, said getter electrode having a high affinity for oxygen and being suitably arranged on the inside of said high vacuum manufacturing chamber so that the exposed areas of said metallized areas of said substrates are substantially surrounded by a surface of said getter electrode; said substrate holder and said getter electrode being electrically isolated from each other means for applying a radio frequency voltage to said substrates independently of said means to apply a voltage to said getter electrode, said radio frequency voltage causing cathode sputtering of said metallized areas of said substrates.
Claim 13
Dependent Claim 18 words
The apparatus of claim 10 wherein said substrate holder is rotatably mounted to the top of said chamber.
Claim 14
Dependent Claim 27 words
The device of claim 11 wherein said substrate holder is electrically insulated and also serves as said means for applying a radio frequency voltage to said substrates.
Claim 15
Dependent Claim 19 words
The apparatus of claim 12 wherein each getter electrode is mounted to one of the walls of said chamber.
Claim 16
Dependent Claim 12 words
The apparatus of claim 13 wherein each getter electrode is electrically insulated.
Claim 17
Dependent Claim 21 words
The apparatus of claim 12 wherein each getter electrode is made of a gettering material having a high affinity for oxygen.
Claim 18
Dependent Claim 13 words
The apparatus of claim 15 wherein each getter electrode is made of aluminum.
Claim 19
Dependent Claim 13 words
The apparatus of claim 15 wherein each getter electrode is made of titanium.
Claim 20
Dependent Claim 16 words
The apparatus of claim 15 wherein each getter electrode is electrically insulated against said chamber walls.
Claim 21
Dependent Claim 21 words
The apparatus of claim 15 wherein said getter electrode is a spherical segment which conforms in shape with said substrate holder.
Claim 22
Dependent Claim 23 words
The apparatus of claim 18 or 19 wherein said chamber further comprises an inlet means through which a noble gas may be introduced.
Claim 23
Dependent Claim 28 words
The apparatus of claim 20 wherein said means for applying a radio frequency voltage is a radio frequency voltage conduit which is suitably attached to said substrate holder.
Claim 24
Dependent Claim 10 words
The apparatus of claim 21 further comprising an evaporation chamber.
Claim 25
Dependent Claim 18 words
The apparatus of claim 22 further comprising a separation valve separating said vacuum chamber from said evaporation chamber.
Claim 26
Dependent Claim 21 words
The apparatus of claim 23 further comprising a diffusion pump for creating and maintaining a vacuum in the chambers when necessary.
Claim 27
Dependent Claim 223 words
A sputter cleaning apparatus for forming contaminant free surfaces on metallized areas of a substrate comprising: a dual purpose chamber having a high vacuum manufacturing chamber portion having resilient seals and an evaporation chamber portion, said vacuum portion and said evaporation portion being separated by a separation valve; inlet and outlet ports in said high vacuum manufacturing chamber portion having resilient seals, of facilitating the introduction and evacuation of gases to and from said chamber; a diffusion pump being suitably connected to said outlet ports for creating and maintaining a vacuum when necessary; an electrically insulated substrate holder for receiving and holding substrates, said substrate holder being rotatably arranged in said chamber and being rotatably supported by a motor via a radio frequency voltage conduit; at least one getter electrode and means for applying a voltage thereto for generating a gas plasma, said electrode being made of a gettering material having a high affinity for oxygen; each electrode being electrically insulated against said chamber walls and said substrate holder and being arranged so that the exposed areas of said metallized areas of said substrates are substantially surrounded by a surface of said getter electrode; said radio frequency voltage conduit applying a radio frequency voltage to said substrate holder independently of said means to apply a voltage to said getter electrode; causing cathode sputtering.
Claim 28
Dependent Claim 223 words
A sputter cleaning apparatus for forming contaminant free surfaces on metallized areas of a substrate comprising: a dual purpose chamber having a high vacuum manufacturing chamber portion having resilient seals and an evaporation chamber portion, said vacuum portion and said evaporation portion being separated by a separation valve; inlet and outlet ports in said high vacuum manufacturing chamber portion having resilient seals, of facilitating the introduction and evacuation of gases to and from said chamber; a diffusion pump being suitably connected to said outlet ports for creating and maintaining a vacuum when necessary; an electrically insulated substrate holder for receiving and holding substrates, said substrate holder being rotatably arranged in said chamber and being rotatably supported by a motor via a radio frequency voltage conduit; at least one getter electrode and means for applying a voltage thereto for generating a gas plasma, said electrode being made of a gettering material having a high affinity for oxygen; each electrode being electrically insulated against said chamber walls and said substrate holder and being arranged so that the exposed areas of said metallized areas of said substrates are substantially surrounded by a surface of said getter electrode; said radio frequency voltage conduit applying a radio frequency voltage to said substrate holder independently of said means to apply a voltage to said getter electrode; causing cathode sputtering.
Claim 29
Dependent Claim 13 words
The device of claim 25 wherein each getter electrode is made of aluminum.
Claim 30
Dependent Claim 13 words
The device of claim 25 wherein each getter electrode is made of titanium.
Claim 31
Dependent Claim 21 words
The device of claim 25 wherein each getter electrode is a spherical segment which conforms in shape with said substrate holder.
Claim 32
Dependent Claim 13 words
The method of claim 1 wherein there is more than one getter electrode.
Claim 33
Dependent Claim 13 words
The apparatus of claim 10 wherein there is more than one getter electrode.

References Cited (Backward Citations)

US3298863A Cited
US3691053A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1990-11-02 1991-05-04 1991-11-03 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1994-11-02 1995-05-04 1995-11-03 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1998-11-02 1999-05-04 1999-11-03 $7700.00 Window Closed / Lapsed

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