Method of fabricating stacked N-O-N ultrathin gate...

Details Method of fabricating stacked N-O-N ultrathin gate... Method of fabricating stacked N-O-N ultrathin gate...

1996-09-16

2001-11-20

Bowers, Charles (Department: 2813)

Semiconductor device manufacturing: process

Coating of substrate containing semiconductor region or of...

Insulative material deposited upon semiconductive substrate

C438S787000, C438S769000, C438S287000, C438S216000, C438S591000, C438S264000, C438S261000

Reexamination Certificate

active

06319857

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an improved semiconductor device and a method of manufacturing a semiconductor device.
BACKGROUND OF THE INVENTION
In the semiconductor industry, the basic steps of the conventional method of manufacturing P-doped gate structures have been fairly standardized. The process begins with the silicon substrate upon which a layer of barrier oxidation is positioned. After various steps, areas of field oxide become situated between block of barrier nitride. Gate oxide is then typically grown between the field oxide. This step of growing the gate oxide is generally referred to as “gate oxidation.”
After various other steps, a block of polysilicon is situated above the gate oxide. Finally, boron difluoride (BF
2
) is implanted in the polysilicon. Subsequent to the BF
2
implantation step, rapid thermal anneal (RTA) is typically initiated wherein the wafers are heated and the implants are activated and driven.
The conventional method of gate oxidation has several problems. One such problem is that it is typical for the surface of a silicon to have some particles on its surface. When an electrical stress is applied to the device with a particle on the silicon, the device will deteriorate much sooner than if the silicon had no particle on it.
Another problem prevalent in the conventional method for manufacturing semiconductor devices is caused by a defect located on the silicon. These defects can be created by the various steps taken in the manufacturing process utilizing temperature cycles and implantation. These defected areas have a tendency to leak charges, and consequently, will typically be much weaker than the other areas of the silicon.
A third problem appears when nitride is used in place of the gate oxide. When a plasma enhanced chemical vapor deposition (CVD) method is used for the nitride deposition, there will be an unavoidable given amount of hydrogen in the nitride. These hydrogen atoms cause a void in the matrix of elements and creates an excessive potential for cracking in the dielectric, thereby causing the device to be susceptible to any failures.
A further problem in the conventional methods for manufacturing semiconductor devices is caused by the use of BF
2
to dope polysilicon in P-channel devices. The boron from the BF
2
diffuses readily through the oxide, thereby degrading the oxide.
What is needed is an improved semiconductor device and improved method of manufacturing a semiconductor device which avoids the problems prevalent in the conventional methods. The present invention addresses such a need.
SUMMARY OF THE INVENTION
The present invention is an improved semiconductor device and an improved method of manufacturing a semiconductor device. The present invention deposits a layer of oxynitride where gate oxidation would normally take place. Alternatively, the method according to the present invention uses a plurality of layers of dielectric material where gate oxidation would normally take place including a layer of oxynitride having a nitrogen content. The layer of oxynitride is deposited under a predetermined pressure using a stream of gas, wherein insensitivity to defects on a surface of the substrate results from the oxynitride layer.
A method for manufacturing a semiconductor device according to the present invention is comprised of the steps of providing a substrate; providing a field oxide coupled to the substrate; providing a plurality of layers of dielectrics coupled to the substrate and the field oxide; providing a layer of polysilicon over the plurality of layers of dielectrics; and implanting a doping substance into the polysilicon layer, wherein the nitrogen content impedes diffusion of the doping substance through the field oxide.
Another method for manufacturing a semiconductor device according to the present invention is comprised of the steps of providing a substrate; providing a field oxide coupled to the substrate; depositing a layer of oxynitride over the substrate; and providing a layer of polysilicon over the oxynitride layer.


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