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Controlling Wafer Temperature During Sputter Etching to Control Etch Uniformity

IP.com Disclosure Number: IPCOM000039659D
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Brown, WW: AUTHOR [+3]

Abstract

The temperature of wafers is monitored by an infrared detector while the wafers are being etched. The etch rate is adjusted in order to maintain the desired temperature to provide uniform etch distribution. In the DC sputter etching of semiconductor wafers the etch rate increases exponentially as the wafer temperature is increased. Conventional techniques to control wafer temperature during etching include varying the current or maintaining a constant voltage in the sputter etch power supply, etching for a fixed period of time, and maintaining a constant cooling gas pressure and flow. In the present technique, the wafer temperature is measured and the voltage of the sputter power supply is adjusted in order to vary the etch rate to maintain the wafer temperature at a desired level.

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Controlling Wafer Temperature During Sputter Etching to Control Etch Uniformity

The temperature of wafers is monitored by an infrared detector while the wafers are being etched. The etch rate is adjusted in order to maintain the desired temperature to provide uniform etch distribution. In the DC sputter etching of semiconductor wafers the etch rate increases exponentially as the wafer temperature is increased. Conventional techniques to control wafer temperature during etching include varying the current or maintaining a constant voltage in the sputter etch power supply, etching for a fixed period of time, and maintaining a constant cooling gas pressure and flow. In the present technique, the wafer temperature is measured and the voltage of the sputter power supply is adjusted in order to vary the etch rate to maintain the wafer temperature at a desired level. Referring to the drawing, the wafers 1 are supported on a dome 2 and placed in a vacuum chamber 3. The chamber 3 is typically grounded and a DC voltage is applied to the dome 2 from a power supply 4. The voltage of the power supply 4 is varied to control the etch rate. An infrared measurement system 5 is focused through a sapphire window into the backside of a wafer 1. The infrared system 5 provides a signal corresponding to the wafer temperature to the power supply 4. The wafer temperature is maintained at a predetermined setpoint by increasing or decreasing the power supply voltage to raise or lower the s...