Method for improving the uniformity of wafer-to-wafer film...

Details Method for improving the uniformity of wafer-to-wafer film... Method for improving the uniformity of wafer-to-wafer film...

1998-12-30

2001-04-17

Nelms, David (Department: 2818)

Semiconductor device manufacturing: process

Coating of substrate containing semiconductor region or of...

Insulative material deposited upon semiconductive substrate

C438S792000, C438S798000, C427S570000, C427S585000

Reexamination Certificate

active

06218320

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Taiwan application serial no. 87110515, filed Jun. 30, 1998, the full disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method for forming films, and in particular to a method for improving the uniformity of wafer-to-wafer film thicknesses used in a plasma-enhanced chemical vapor deposition (PECVD) reactor.
2. Description of the Related Art
A PECVD system includes a reactor, a gas transmission system, an exhaust system, and a process control system. This specification focuses on the reactor while the other systems not related to the invention are not further described. The Novellus PECVD system is taken as an example, and the reactor system thereof is shown in FIG.
1
. In
FIG. 1
, an RF power source
12
is applied to
6
shower heads
14
in a reactor
10
, and
6
wafers
16
is placed on a heater block
18
, such that the wafers
16
is opposite to the shower head
14
.
The PECVD system is typically used to deposit dielectric films. In semiconductor technology, two metal layers are isolated by a dielectric layer for the purpose of insulation. Therefore, the property, quality and thickness of the dielectric layer are significant considerations.
As an example, a tetra-ethyl-ortho-silicate (TEOS) is traditionally used to serve as a dielectric layer for isolating metal layers. In the Novellus PECVD system, a TEOS layer is deposited at a high temperature of 300-400° C. Furthermore, the shower head
14
does not have any temperature control device mounted on it and the thicknesses of TEOS layers are determined only by setting a deposition time. Therefore, the unstable temperature of the shower heads causes the TEOS layers to be deposited with varying thicknesses on the first several wafers. The temperature of the shower heads
14
stabilizes only after a certain number of wafers have been subjected to a deposition process. Once the temperature stabilizes, the thicknesses of the TEOS layers can also reach a uniform value. Referring to
FIG. 2
, the y-axis indicates the thicknesses of TEOS layers or the temperature of the shower heads while the x-axis indicates the number of wafers on which the deposition process has been completed.
Therefore, when TEOS layers are deposited by using a prior PECVD system, the uniformity of the thicknesses of the TEOS layers varies from batches to batches. The obvious difference in thickness among the wafers makes the quality of products very difficult to control, resulting in poor yield.
Moreover, after the PECVD system operates for a period of time, it is necessary to perform preventive maintenance or open chamber clean for the system to continue to work properly. However, it takes time to heat the heater block to production temperature, increasing the time required to start the PECVD system after implementing preventive maintenance or cleaning.
SUMMARY OF THE INVENTION
A first object of the invention is to provide a method which is able to resolve the problem of the uneven thicknesses of films on wafers.
A second object of the invention is to provide a method which not only avoids poor uniformity among films on wafers after finishing preventive maintenance or cleaning, but also shortens the heating time of the heater block in a PECVD system.
To attain the objects mentioned above, a method for manufacturing film by using a PECVD system according to the invention includes the following steps. Prior to film deposition, a shower head in a PECVD system is heated to production temperature by use of a plasma in coordination with heating of a heater block, thereby allowing the entire system (including the shower head) to reach a stable temperature. Subsequently, a gas source output via the shower head is provided, and then a RF plasma is generated to form a film on a wafer. Therefore, the problem of the uneven thicknesses of films on wafers is resolved.
In addition, if the shower heads and the heater block are concurrently heated, wherein the heater block can also be heated by the plasma after preventive maintenance or open chamber cleaning the PECVD system, the heating time of the heater block is further shortened.
Moreover, since a temperature measuring device and/or a heating element additionally mounted on the shower heads accurately measures the temperature of the shower heads, the time taken to heat the shower heads is optimized. And since the heating element can be used to cooperate with or displace the step of plasma heating, the temperature of the shower heads is easily controlled.


REFERENCES:
patent: 5120680 (1992-06-01), Foo et al.
patent: 5888591 (1999-03-01), Gleason et al.

Affiliated with

Also associated with

Rating

Method for improving the uniformity of wafer-to-wafer film... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method for improving the uniformity of wafer-to-wafer film..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for improving the uniformity of wafer-to-wafer film... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2453029