A new technique has been developed to measure etching or deposition rate uniformity in situ using a CCD camera which views the wafer during plasma processing. The technique records the temporal modulation of plasma emission or laser illumination reflected from the wafer; this modulation is caused by interferometry as thin films are etched or deposited. The measured etching rates compare very well with those determined by Helium-Neon laser interference. This technique is capable of measuring etching rates across 100-mm or larger wafers. It can resolve etch rate variations across a wafer or within a die. The invention can also be used to make endpoint determinations in etching operations as well as measuring the absolute thickness of thin films.

Apparatus and method for real-time measurement of thin film layer thickness and changes thereof

A method for fabricating a semiconductor device includes forming a recess gate over a semiconductor substrate. A gate spacer is formed on a sidewall of the recess gate. The semiconductor substrate in a landing plug contact region is soft-etched to form a recess having a rounded profile. A sidewall spacer is formed over the gate spacer and a sidewall of the recess. An insulating film is formed over the semiconductor substrate. The insulating film is selectively etched to form a landing plug contact hole. A conductive layer in the landing plug contact hole is filled to form a landing plug.

Semiconductor Device and Method for Fabricating the Same

The invention provides a method of forming shallow SIMOX (Separation by IMplantation of OXygen) substrates by implantation of molecular oxygen ions (O 2 +), instead of implanting atomic oxygen ions (O+) as is done in prior art SIMOX processes. Use of molecular oxygen ions (O 2 +) doubles the yield of oxygen atoms implanted for each unit of electric charge deposited in the wafer. The resultant structure, after annealing, has a defect density which is not substantially different from SIMOX processing using atomic oxygen ions (O+). An alternative method for implanting molecular nitrogen ions is also disclosed.

Shallow SIMOX processing method using molecular ion implantation

A preferred embodiment of this invention is a silicon-on-insulator structure comprising a semiconductor substrate (e.g. Si 36), a buried insulator layer (e.g. SiO 2 34) overlaying the substrate, wherein the buried layer is buried at two or more predetermined depths, and a surface silicon layer (e.g. Si 32) overlaying the buried insulator, wherein the surface silicon layer has two or more predetermined thicknesses. Generally, by patterning and etching a screening material (e.g. SiO 2 30) prior to ion implantation, preselected areas of the substrate with less or no screen material are formed with a thicker surface silicon layer, while other areas with more screen material are formed with a thinner surface silicon layer. The areas of different surface silicon thickness can be used to implement devices with different characteristics based on those thicknesses, within the same integrated circuit. Generally, relatively thinner regions can be used for faster speed devices and relatively thicker regions can be used for greater current carrying capability. The novel technique of depositing, patterning and etching a layer of screening material before implantation can also be used to create a substrate with both bulk and SOI substrate regions, with different portions of a circuit built in each region. Generally, such a substrate can be used to create integrated circuits that have high voltage isolation between different blocks of the circuit. The SOI/bulk substrate can also be used to fabricate integrated circuits which contain low voltage logic and which also regulate large amounts of current at high voltage.

Varying the thickness of the surface silicon layer in a silicon-on-insulator substrate

Active pixel sensors for a high quality imager are fabricated using a silicon-on-insulator (SOI) process by integrating the photodetectors on the SOI substrate and forming pixel readout transistors on the SOI thin-film. The technique can include forming silicon islands on a buried insulator layer disposed on a silicon substrate and selectively etching away the buried insulator layer over a region of the substrate to define a photodetector area. Dopants of a first conductivity type are implanted to form a signal node in the photodetector area and to form simultaneously drain/source regions for a first transistor in at least a first one of the silicon islands. Dopants of a second conductivity type are implanted to form drain/source regions for a second transistor in at least a second one of the silicon islands. Isolation rings around the photodetector also can be formed when dopants of the second conductivity type are implanted. Interconnections among the transistors and the photodetector are provided to allow signals sensed by the photodetector to be read out via the transistors formed on the silicon islands.

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Silicon-on-insulator (SOI) active pixel sensors with the photosite implemented in the substrate

A method for producing buried oxide layers in selected portions of a semiconductor substrate including the steps of applying a patterned mask made from a high-density material over a semiconductor substrate and selectively forming buried oxide layers by oxygen ion implantation. The high-density material of the mask is preferably tungsten, but can also be made from other suitable materials such as silicon nitride. A MOS transistor is made by the process of the present invention by applying the high-density mask material over the gate of the transistor, and forming buried oxide layers by ion implantation beneath only the source region and drain region of the transistor. The completed MOS transistor has the characteristics of reduced drain and source capacitance, reduced leakage, and faster response, but does not suffer from the floating-body effect of MOS transistors made by SOI processes.

Method for making patterned implanted buried oxide transistors and structures

Plasma etching has become an important technology in the fabrication of integrated circuits. The importance of this technology will increase as the minimum geometry features continue to decrease to the submicron region. Process monitoring is a very desirable feature in maintaining the precise control that is required of plasma etching for VLSI circuits. This paper describes two optical methods of process monitoring and end point detection for plasma etching. Examples are presented for emission spectroscopy, and an optical reflection method. A direct comparison of these methods as end point detection monitors is also made.© (1981) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Paul J. Marcoux

Papers

Method for making patterned implanted buried oxide transistors and structures

Optical Methods For End-Point Detection In Plasma Etching

Verfahren zur herstellung von vergrabenen oxidschichten und mos-transistor