摘要:

The thickness of gate dielectrics for complementary metal–oxide–semiconductor (CMOS) devices with 0.1 to 0.35 μm gate dimensions is typically 4 to 7 nm. Besides serving as an insulator, the dielectric, usually SiO2, also acts as a diffusion barrier between the doped polycrystalline silicon gate material and the Si substrate (channel). Dopant diffusion from the poly‐gate into the device channel may cause undesirable shifts in the transistor threshold voltage. The determination of dopant diffusion through the gate dielectric into the channel region of the transistor is necessary to optimized device processing. This paper reports a method, resonance ionization mass spectrometry (RIMS), to measure dopant distribution profiles near the gate oxide. The pertinent spectroscopy of sputtered B and P atoms is demonstrated. Matrix effects are shown to be diminished. RIMS depth profiles of CMOS test structures show both dopant penetration into the channel and blockage by the gate oxide depending upon annealing conditions.

ISSN:1071-1023    

DOI:10.1116/1.587993

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Advances in memory IC technology for dynamic random access memory (DRAM) devices have come about from a reduction in individual cell thickness with a corresponding increase in cell depth in order to maintain the same stored capacitance value. As the memory size on DRAM devices rises, memory cells must get deeper making the process of measuring depth more difficult. In this article we describe a novel, nondestructive, noncontact metrology technique which utilizes both two‐dimensional diffraction analysis and multivariate statistical methods to measure deep trench depth in the 6–9 μm range. We applied this technique to two DRAM product wafers and obtained a successful prediction of trench depth for both wafers with an accuracy of ±0.04 μm, or ±0.56% variation relative to scanning electron microscope measurements of the same samples.

ISSN:1071-1023    

DOI:10.1116/1.587994

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Numerical simulation results are presented for microscopic profile evolutions of deposited metal films in trench structures under ionized magnetron sputter deposition. The model used for the simulations takes account of the deposition of both ionized and neutral metal species and sputtering (i.e., etching) of the deposited film by the bombardment of metal and inert‐gas (such as argon) ions. The evolution of the surface topography is calculated numerically using the shock‐ tracking algorithm. Numerical results are also compared with experimental observations. A primary application of this metal deposition technique is interconnect metallization on semiconductors.

ISSN:1071-1023    

DOI:10.1116/1.587995

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

The transport of silicon vapor from an electron‐beam evaporation source through argon and hydrogen gas in pressures near 1.0 mTorr has been studied. The flux–distance relationships for the effusion/diffusion of the evaporant through the device are found to vary with the type of filling gas. The investigation includes both a simple theoretical model and experiment. The results of each study are in good agreement. Cross sections for the energy‐averaged momentum transfer collisions of silicon with the filling gases (argon, hydrogen) at thermal energies have been determined.

ISSN:1071-1023    

DOI:10.1116/1.587996

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Submicron Al–Si–Cu filled via formation by a high‐temperature sputter deposition method employing Ti underlayers and via electrical properties were studied. It was found that degree of filling, via chain resistance, and variation of the via chain resistance depend on the Ti underlayer thickness. The via chain resistance and its variation with thick Ti underlayer (50–100 nm) are smaller than those with thin Ti underlayer (20 nm). This might be because of improvement in wettability of Al–Si–Cu films at via sidewall, which is caused by uniform interfacial reaction between the Ti underlayer and the Al–Si–Cu film. It was shown that Al films at the via holes consist of one or two single crystalline. With Ti underlayer thickness of 20 nm, electromigration resistance for Al–Si–Cu filled via chains with low resistance was a factor of about 20 times greater than that of Al unfilled vias by a conventional sputter deposition method. On the contrary, the filled via chains with high resistance failed at an initial stage during electromigration testing. Also, it was found that via resistance increase during electromigration is caused by the depletion of Al–Ti–Si compounds in the vicinity of the Al plug via interface.

ISSN:1071-1023    

DOI:10.1116/1.587997

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

The primary metallization technique in the semiconductor industry for the past decade has been magnetron sputtering. The general industry trend towards damascene processing requires the capability to fill trenches and vias with sub‐one‐half micron widths and aspect ratios (AR) as high as 3:1. At these dimensions and geometries, the angular distribution of magnetron sputtered atoms results in the production of voids during deposition. A new approach to this problem is directional sputter deposition, where neutrals generated from magnetron sputtering are ionized through an inductively coupled rf plasma and accelerated towards the substrate via a small dc bias on the substrate, causing a significant portion of the flux to arrive at normal incidence. The experimental parameters of this process have been explored by depositing Cu on patterned Si wafers. The parameters have varying effects on the morphology of the deposited layer, which indicate relationships between the parameters and the ion‐to‐neutral ratio, the total flux, and the average ion energy. The ionized magnetron sputter deposition process has been used successfully to fill trenches of 600 nm width and 1.1 AR with Cu near room temperature, and appears to be extendable to more aggressive dimensions.

ISSN:1071-1023    

DOI:10.1116/1.587998

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

The effects of low‐energy plasma bombardment have been quantified for the first time. The plasma effects on thin copper films (∼50 nm) have been studied by exposing these films to magnetically enhanced Ar plasmas. The Cu films deposited by different techniques were exposed to plasmas by systematically varying the exposure time and the rf power. The microstructural changes (grain size) in the films were studied using transmission electron microscopy. Grain growth is observed in thin Cu films when the films are exposed to low‐energy (63–114 eV) Ar plasmas. rf power is shown to have a strong influence on the microstructure of Cu films. The microstructural changes in sputtered and evaporated films are quite significant whereas the plasma bombardment has less effect on chemical vapor deposited films. These changes occur very rapidly and cannot be attributed solely to the thermal effects especially at low rf powers (300–500 W). The effect of temperature, however, becomes significant at 700 W. The initial microstructure of the film also plays a role in grain growth during plasma exposure.

ISSN:1071-1023    

DOI:10.1116/1.587999

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

The spatially resolved surface chemical composition or ‘‘chemical topography’’ of submicron features [polycrystalline silicon (poly‐Si) masked with photoresist (PR) lines] etched in high density, low pressure helical resonator Cl2/O2plasmas has been quantitatively determined using angle resolved x‐ray photoelectron spectroscopy (XPS). The chemical topography of plasma etched microelectronic materials is important in understanding how impinging ions and neutrals interact with surfaces to influence etched profiles. The spatial origin of XPS signals was determined from a combination of geometric shadowing of photoelectrons by adjacent features, electrostatic charging of insulating surfaces, XPS signal calibration versus take‐off angle, x‐ray attenuation, and geometric modeling. Equal line and space width (0.75–2.0 μm) features, unmasked poly‐Si, and unpatterned PR surfaces were examined following plasma etching and vacuum sample transfer. For pure Cl2plasmas, Cl surface concentration was found to be similar for horizontal and vertical surfaces of the poly‐Si and PR. Only a small amount of Si was found on the PR sidewall, and similarly, little C or O was observed on the side of the poly‐Si features, indicating that sidewall passivation is not occurring. O coverage on all surfaces increased with O2addition to the plasma. For Cl2/5% O2plasmas, a small amount of O was found on the poly‐Si trench bottom, and more (but still submonolayer) on the poly‐Si sidewall. Also, more Cl, O, and Si were found on the PR sidewall with 5% O2. For Cl2/10% O2plasmas, rough surfaces were observed by scanning electron microscopy (SEM). On poly‐Si trench bottoms, O coverage is comparable to Cl at roughly a monolayer. On poly‐Si sidewalls, O and Cl coverages are again comparable, but the O coverage is about double that found on the trench bottoms. The most dramatic effect by far at 10% added O2is the formation of a thick SiOxClylayer (wherex≊y≊1) on the side of the PR, detected by both XPS and SEM. The quantitative analysis method developed in this study is readily applicable to other etching gases and materials.

ISSN:1071-1023    

DOI:10.1116/1.588355

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Interface damage and oxidation behavior are compared for electron cyclotron resonance plasma oxidation of silicon for two different plasma system configurations: a conventional system where the plasma is generated and extracted normal to the Si wafer surface, and another system where the plasma is made uniform by developing the magnetic field parallel to the substrate using permanent magnets outside the chamber and antennas inside, viz. distributed electron cyclotron resonance (DECR) plasma. Samples were compared using spectroscopic ellipsometry, nuclear reaction analysis, and transmission electron microscopy. Less damage was observed in the DECR plasma configuration, but otherwise the systems were comparable.

ISSN:1071-1023    

DOI:10.1116/1.588356

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Reactive ion etching of Si and Ge in SF6–O2is investigated. Etch rate shows that Si etching is selective with respect to Ge in SF6–O2(O2<50%); the reverse is observed in SF6–O2(O2≳50%). In agreement with the compared evolution of the F and O concentration in the plasma and of the etch product formation rate obtained respectively, by optical emission spectroscopy and mass spectrometry, the x‐ray photon spectroscopy surface analysis reveals that the growth of a SiOxFylayer quenches the Si etching whereas the formation of GeOxFydoes not inhibit Ge etching. Using a simple model, an experimental surface reactivity is defined and expressed in function of the experimental data. Results suggest a different behavior for sulfur and oxygen on both materials.

ISSN:1071-1023    

DOI:10.1116/1.588357

出版商:American Vacuum Society    

年代:1995

数据来源: AIP