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EP0451571A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Sputtering process for forming aluminum layer over stepped semiconductor wafer

Assignee: Applied Materials Inc

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Filing: 1991-03-21

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Granted: —

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Expires: 2011-03-21

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Abstract

Abstract In a multistep aluminum sputtering process aluminum is sputtered onto the surface of a semiconductor wafer (13) and low areas (14) between closely spaced apart raised portions (11, 12) on the wafer, such as closely spaced apart steps, narrow trenches, or small diameter vias, are completely filled in by the sputtered aluminum (20). This results in the formation of an aluminum layer (20) which is not thinned out in such low areas, and which has a surface which ranges from substantially planar to a positive slope, such as shown at (24') and (26') in Figure 2. The first step is carried out by sputtering from about 20 to about 200 nm (200 to about 2000 Angstroms) of aluminum while the wafer temperature is within a range of from about 50°C to about 250°C and the sputtering plasma is at a power level of from about 1 to about 16 kilowatts. The power level range is then changed to from about 14 to about 20 kilowatts, a DC or AC bias is applied to the wafer, and aluminum is then sputtered either for an additional time period of about 20 to about 45 seconds or until the wafer temperature reaches 500°C, whichever occurs first, in a second step. Then the back side of the wafer is contacted by a thermally conductive gas to control the wafer temperature while further aluminum is optionally sputtered onto the wafer for an additional 0 to 45 seconds in a third step.

Inventors

👤 Chien-Rhone Wang

Bibliographic Details

Application Number —

Jurisdiction EP

Data Source google_patents

Last Synchronized 2026-10-30 08:18

CPC Classifications

H; H10; H10W; H10W20/00; H10W20/01; H10W20/031; H10W20/062; H10P; H10P14/00; H10P14/40; H10P14/42; H10P14/44; H10W20/056

Claims Analysis

Total Claims: 10

Claim 1

Independent Claim 156 words

A sputtering process for forming an aluminum layer over a stepped semiconductor wafer which comprises: a. sputtering from 20 to 200 nm (200 to 2000 Å) of aluminum from a target onto said wafer in a first deposition step while maintaining a power level on said traget of from 1 kilowatt to 16 kilowatts; b. changing the power level to at least about 14 kilowatts, preferably to a range of from 14 to 20 kilowatts, and sputtering aluminum for an additional 25 to 45 seconds or until the wafer temperature reaches about 500°C, whichever occurs first, during a second deposition step, while applying a DC or AC bias to the wafer; and c. then contacting the backside of the wafer with a thermally conductive gas to maintain said wafer at a temperature not exceeding about 500°C while optionally sputtering additional aluminun onto said wafer for an additional 0 to 45 seconds in a third deposition step.

Claim 2

Dependent Claim 43 words

The process of claim 1 wherein said bias is either a DC bias which ranges from -100 to -150 volts or an AC bias which ranges from 300 to 500 volts peak to peak, said bias ranging preferably from 400 to 1000 watts.

Claim 3

Dependent Claim 24 words

The process of claim 1 or 2, wherein said first step is carried out while maintaining a wafer temperature of from 50°C to 250°C.

Claim 4

Dependent Claim 57 words

The process of one of the preceding claims, wherein the target voltage is maintained within a range of from -400 volts to -600 volts throughout the process and/or the pressure in said sputtering chamber is maintained within a range of from 1.3 · 10⁻³ mbar (1 milliTorr) to 10.4 · 10⁻³ mbar (8 milliTorr) throughout the process.

Claim 5

Dependent Claim 23 words

The process of one of the preceding claims, wherein said wafer temperature is not allowed to exceed about 400°C during said second step.

Claim 6

Dependent Claim 38 words

The process of one of the preceding claims, wherein said thermally conductive gas couples said wafer to a heater maintained at a temperature not exceeding about 450°C to control the temperature of said wafer during said third step.

Claim 7

Dependent Claim 30 words

The process of one of the preceding claims, wherein a wafer support platform is initially heated to a temperature of from 250°C to 450°C prior to said first sputtering step.

Claim 8

Dependent Claim 30 words

The process of claim 7, wherein said heated wafer support platform is used to contact said wafer and to raise said wafer thereon to a sputtering position in said chamber.

Claim 9

Dependent Claim 57 words

The process of one of the preceding claims, wherein said thermally conductive gas is admitted to a sealed region between the upper surface of a wafer support platform and the backside of said wafer, after said second step to thermally couple said wafer to said support platform to control the wafer temperature during said third deposition step.

Claim 10

Dependent Claim 35 words

The process of one of the preceding claims for sputtering an aluminum layer having a surface which ranges from substantially planar to a positive slope over a semiconductor wafer having closely spaced apart raised portions.

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