Etching a substrate: processes – Gas phase etching of substrate – Application of energy to the gaseous etchant or to the...
Reexamination Certificate
1998-09-10
2001-05-15
Scheiner, Laurie (Department: 1648)
Etching a substrate: processes
Gas phase etching of substrate
Application of energy to the gaseous etchant or to the...
C216S067000, C216S074000, C156S192000, C156S345420, C315S111210, 43, C204S192320
Reexamination Certificate
active
06231776
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to plasma processing. More particularly, one aspect of the invention is for greatly improved plasma processing of devices using an in-situ temperature application technique. Another aspect of the invention is illustrated in an example with regard to plasma etching or resist stripping used in the manufacture of semiconductor devices. The invention is also of benefit in plasma assisted chemical vapor deposition (CVD) for the manufacture of semiconductor devices. But it will be recognized that the invention has a wider range of applicability. Merely by way of example, the invention also can be applied in other plasma etching applications, and deposition of materials such as silicon, silicon dioxide, silicon nitride, polysilicon, among others.
Plasma processing techniques can occur in a variety of semiconductor manufacturing processes. Examples of plasma processing techniques occur in chemical dry etching (CDE), ion-assisted etching (IAE), and plasma enhanced chemical vapor deposition (PECVD), including remote plasma deposition (RPCVD) and ion-assisted plasma enhanced chemical vapor deposition (IAPECVD). These plasma processing techniques often rely upon radio frequency power (rf) supplied to an inductive coil for providing power to produce with the aid of a plasma.
Plasmas can be used to form neutral species (i.e., uncharged) for purposes of removing or forming films in the manufacture of integrated circuit devices. For instance, chemical dry etching is a technique which generally depends on gas-surface reactions involving these neutral species without substantial ion bombardment.
In a number of manufacturing processes, ion bombardment to substrate surfaces is often undesirable. This ion bombardment, however, is known to have harmful effects on properties of material layers in devices and excessive ion bombardment flux and energy can lead to intermixing of materials in adjacent device layers, breaking down oxide and “wear out,” injecting of contaminative material formed in the processing environment into substrate material layers, harmful changes in substrate morphology (e.g. amophotization), etc.
Ion assisted etching processes, however, rely upon ion bombardment to the substrate surface in defining selected films. But these ion assisted etching processes commonly have a lower selectivity relative to conventional CDE processes. Hence, CDE is often chosen when high selectivity is desired and ion bombardment to substrates is to be avoided.
In generally most, if not all, of the above processes maintain temperature in a “batch” mode. That is, the temperature of surfaces in a chamber and of the substrate being processed in such chamber are controlled to be at a substantially a single value of temperature during processing.
From the above it is seen that an improved technique, including a method and apparatus, for plasma processing is often desired.
SUMMARY OF THE INVENTION
The present invention provides a technique, including a method and apparatus, for fabricating a product using a plasma discharge. One aspect of the present technique relies upon multi-step etching processes for selectively removing a film on a workpiece using differing temperatures. It overcomes serious disadvantages of prior art methods in which throughput and etching rate were lowered in order to avoid excessive device damage to a workpiece. In particular, this technique is extremely beneficial for removing resist masks which have been used to effect selective ion implantation of a substrate in some embodiments. In general, implantation of ions into a resist masking surface causes the upper surface of said resist to become extremely cross-linked and contaminated by materials from the ion bombardment. If the cross-linked layer is exposed to excessive temperature, it is prone to rupture and forms contaminative particulate matter. Hence, the entire resist layer is often processed at a low temperature to avoid this particle problem. Processing at a lower temperature often requires excessive time which lowers throughput. Accordingly, the present invention overcomes these disadvantages of conventional processes by rapidly removing a majority of resist at a higher temperature after an ion implanted layer is removed without substantial particle generation at a lower temperature.
In another aspect, the present invention provides a process which utilizes temperature changes to achieve high etch rates while simultaneously maintaining high etch selectivity between a layer which is being pattered or removed other material layers. An embodiment of this process advantageously employs a sequence of temperature changes as an unexpected means to avoid various types of processing damage to the a device and material layers. A novel inventive means for effecting a suitable controlled change in temperature as part of a process involves the use of a workpiece support which has low thermal mass in comparison to the heat transfer means. In an aspect of this invention, a fluid is utilized to change the temperature of a workpiece. In another aspect, the thermal capacity of a circulating fluid is sufficiently greater than the thermal capacity of the workpiece support that it permits maintaining the workpiece at a substantially uniform temperature.
Still another aspect of the invention provides an apparatus for etching a substrate in the manufacture of a device using different temperatures during etching. The apparatus includes a chamber and a substrate holder disposed in the chamber. The substrate holder has a selected thermal mass to facilitate changing the temperature of the substrate to be etched. That is, the selected thermal mass of the substrate holder allows for a change from a first temperature to a second temperature within a characteristic time period to process a film. The present apparatus can, for example, provide different processing temperatures during an etching process or the like.
The present invention achieves these benefits in the context of known process technology. However, a further understanding of the nature and advantages of the present invention may be realized by reference to the latter portions of the specification and attached drawings.
REFERENCES:
patent: 5770099 (1998-06-01), Rice et al.
patent: 5965034 (1999-10-01), Vinogradov et al.
Flamm Daniel L.
Scheiner Laurie
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