Plasma vacuum substrate treatment process and system
a vacuum substrate and treatment process technology, applied in the field of plasma vacuum substrate treatment process and system, can solve the problems of inability to efficiently track the fast variation of gas flow rate, mechanical inertia of the controlled regulation valve is unable to track the variation this fast, and it is no longer possible to efficiently control the bombardment energy.
Inactive Publication Date: 2002-11-14
ALCATEL LUCENT SAS
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- Description
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Benefits of technology
[0018] Another object of the invention is to provide means for obtaining a controlled pressure in the vacuum enclosure using conventional controlled gas aspiration means employing pressure regulator valves but allowing the active gas flowrates to be varied quickly.
Problems solved by technology
One problem is to obtain etching with well-defined outlines, i.e. in which the cavities have side walls that are as regular as possible and perpendicular to the surface of the substrate.
However, it is clear that the etching step lowers the bottom of the cavity relative to the bottom edge of the lateral polymerized protection layer, with the result that an area appears at the bottom of the side face that is not protected by a layer of polymerized material.
Another problem is to optimize performance in terms of etching and protection layer generation.
However, it is apparent that they cannot efficiently track fast variations in the gas flowrates, such as the variations that can occur if it is required to optimize not only the etching steps but also the protection layer generation steps in an etching process according to document WO 94 / 14187 by alternating the etching and protection layer generation steps at a sufficiently high frequency to attain sufficiently regular lateral cavity faces.
If the gas flowrate during the etching step is different from the gas flowrate during the protection layer generation step, the mechanical inertia of the controlled regulation valve is unable to track variations this fast.
Nor does the mechanical inertia of the controlled regulator valve allow rapid setting of the gas pressure to two successive different values to optimize two successive short treatment steps.
Another problem is that if the gas pressure inside the vacuum enclosure varies between two successive steps, this produces a variation in the impedance of the plasma as seen by the controlled bombardment energy generator connected to the substrate, and it is then no longer possible to control the bombardment energy efficiently to assure the regularity of the treatment.
However, a device of the above kind is not able to track fast impedance variations, i.e. variations occurring at a frequency in the order of 1 Hz.
Method used
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Embodiment Construction
[0041] In the embodiment shown in FIG. 1, the plasma vacuum substrate treatment system includes a vacuum enclosure 1 with controlled active gas injection means 2 for injecting gas into the vacuum enclosure 1 and controlled gas aspiration means 3 for aspirating gas out of the vacuum enclosure 1.
[0042] The controlled active gas injection means 2 include an active gas supply pipe 4 connected to the top part 5 of the vacuum enclosure 1 and receiving a first active gas G1 from a first active gas supply 6 and a second active gas G2 from a second active gas supply 7, each active gas supply being associated with a respective flowmeter 8, 9.
[0043] The top part 5 of the vacuum enclosure 1 also includes plasma generating means 10 including a high-frequency excitation generator 11 connected via an excitation impedance adapter 12 to an excitation winding 13. The plasma generating means 10 ionize the gases in the top part of the vacuum enclosure 1 to form a plasma.
[0044] A substrate support 15 in...
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Abstract
In a process for treatment of a substrate placed in a vacuum enclosure, the invention provides for compensating any variation of the active gas supply flowrate through an active gas supply pipe by injecting a complementary flowrate of control gas into an area near controlled gas aspiration means. This circumvents the inability of pressure control systems and impedance matching systems to respond in times of the order of one second to variations of the input active gas flowrate.
Description
[0001] The present invention relates to plasma vacuum treatment (etching or deposition) of a substrate.[0002] Plasma vacuum substrate treatment processes are already known in the art, such as the etching process described in document WO 94 / 14187, in which the substrate is placed in a vacuum enclosure containing active gases injected in particular via controlled active gas injection means and evacuated via controlled gas aspiration means. The active gases are ionized by plasma-generating means. The substrate in the vacuum enclosure receives bombardment electrical energy generated by a controlled bombardment generator to which it is connected.[0003] During an etching step, ions of a reactive material such as sulfur hexafluoride, generated by ionization, are accelerated by the bombardment energy and impinge on the substrate, for example a silicon-based substrate, in areas that are not covered by a mask. The active ions combine with the material of the substrate to form a gaseous substa...
Claims
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IPC IPC(8): C23C16/507H01J37/32H01L21/205H01L21/302H05H1/46H01L21/3065H01L21/3213
CPCH01J37/3244H01L21/32136H01L21/30655H01J37/32449
InventorPUECH, MICHEL
OwnerALCATEL LUCENT SAS