Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – On insulating substrate or layer
Reexamination Certificate
1998-08-10
2001-11-20
Lebentritt, Michael (Department: 2824)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
On insulating substrate or layer
C438S308000, C438S298000
Reexamination Certificate
active
06319759
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates generally to semiconductor manufacturing and, more particularly, to a method of making oxide and multiple thickness oxide with masked laser oxidation.
2. Related Art
Heretofore, many high performance chips have required more than one gate oxide thickness for MOSFET devices on a chip to optimize the internal circuits which operate at lower voltages and input/output (I/O) circuits which operate at high voltages. Further, the competition for improved circuit performance has driven the device channel scaling down to 0.18 um or shorter to obtain higher current drive from CMOS devices. Gate oxide has been scaled below 5 nm to keep a strong gate control of the device to minimize the short channel effects. The devices operate at 2.5 volt or below in order to maintain the high reliability. Since many other components on the board or in the system still operate at 3.3V or 5V, the input/output circuits of the chip must receive and drive 3.3V or 5V signals. As a result, oxide in these circuits are stressed at higher electrical fields than in the internal logic circuit during product operation, thus degrading chip reliability.
Prior to the present invention, the provision of gate silicon oxide in differing thicknesses has been generally provided through multiple oxidation processes with etching of the first oxide followed by a growth of a thinner oxide layer with a photoresist over the oxide area where thicker oxide is formed. Another process provides a single oxidation process with partial etching of oxide to make thinner oxide with a photoresist on the oxide where thicker oxide is desired. Unfortunately, photoresist processes and the subsequent cleaning processes have been known as a major source of oxide defects in the prior art. A further disadvantage of the prior art method is the complexity of the process in requiring a photolithography and etch.
Another disadvantage of the prior art method is that either a furnace oxidation or rapid thermal oxidation heats up a whole wafer, thus the doping, particularly the channel tailor doping of the high performance device with thinner gate oxide, is moved significantly during the multiple oxidation steps, resulting in the poor device parametric controls and performance degradation.
From above, there is a need for a new method of creating different thickness gate oxide to provide for the differing voltages used within a chip.
SUMMARY OF THE INVENTION
The present invention provides a method to overcome the above-identified problems of the related art through the use of, in general, masked laser oxidation to create gate oxide and/or gate oxide of multiple thicknesses on a chip.
In a first general aspect of the present invention is provided a method of forming oxide comprising the steps of providing a layer; and exposing a first area of the layer upon which oxide is to be grown to an electromagnetic wave during a first exposure. This aspect allows for the creation of oxide without the need for photoresist that contacts the layer. Further, it provides a oxide growth method where heat is localized such that it may be dissipated through the wafer.
In a second general aspect in accordance with the present invention is provided a method of forming oxide, comprising the steps of providing a layer, exposing a first area of the layer upon which oxide is to be grown to a first thickness to an electromagnetic wave and exposing at least one other area of the layer upon which oxide is to be grown to a differing thickness than the first area to an electromagnetic wave. This aspect provides similar advantages so that of the first aspect and further allows for the creation of oxide of differing thicknesses.
In a third general aspect in accordance with the present invention is provided a method of forming oxide comprising the steps of: providing a layer, exposing a first area of the layer upon which oxide is to be grown to an electromagnetic wave having a first power and first duration to form oxide of a first thickness, and exposing at least one other area of the layer upon which oxide is to be grown to an electromagnetic wave having at least one of a differing power and differing duration to form oxide of a differing thickness. This aspect provides similar advantages as the second aspect.
The foregoing and other features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention.
REFERENCES:
patent: 4323589 (1982-04-01), Ray et al.
patent: 5407867 (1995-04-01), Iwasaki et al.
patent: 5412246 (1995-05-01), Dobuzinsky et al.
patent: 5504030 (1996-04-01), Chung et al.
patent: 5576573 (1996-11-01), Su et al.
patent: 5595922 (1997-01-01), Tigelaar et al.
patent: 5597753 (1997-01-01), Sheu et al.
patent: 5605846 (1997-02-01), Ohtani et al.
patent: 5885904 (1999-03-01), Mehta et al.
patent: 5897327 (1999-04-01), Asano et al.
patent: 5904575 (1999-05-01), Ishida et al.
patent: 49096300 (1993-08-01), None
Weiner et al., “Ultrashallow Junction Formation Using Protection Gas Immersion Laser Doping (PGILD),” A Verdant Technologies Technical Brief, pp. 1-6, Aug. 1997.
Furukawa Toshiharu
Hakey Mark C.
Holmes Steven J.
Horak David V.
Ma William H.
International Business Machines - Corporation
Lebentritt Michael
Sabo William D.
Schmeiser Olsen & Watts
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