Ellie Yieh

Surface Related Phenomena in Integrated PECVD/Ozone‐TEOS SACVD Processes for Sub‐Half Micron Gap Fill: Electrostatic Effects

Surface related phenomena of subatmospheric chemical vapor deposition (SACVD) films were systematically studied on different types of plasma enhanced CVD (PECVD) oxides. The PECVD oxides are part of a new and in situ2 step gap fill process consisting of a thin PECVD underlayer and a thick SACVD oxide being proposed for advanced ULSI devices. Differences in deposition rates, wet etch rate, surface morphology, and stress‐temperature behavior of SACVD films deposited on PECVD oxide underlayers and bare silicon substrates were evaluated. For the PECVD underlayers which render surface dependence for the SACVD film, various plasma treatments of the underlayer was used to eliminate the effect. An extensive analysis of the surface and bulk properties of these PECVD oxide underlayers suggests that the occurrence of the surface dependence effects can be attributed to the presence of electronegative species such as fluorine on the surface of the PECVD oxide underlayer.

High Aspect Ratio Trench Filling Using Two‐Step Subatmospheric Chemical Vapor Deposited Borophosphosilicate Glass for <0.18 μm Device Application

As a premetal dielectric, borophosphosilicate glass (BPSG) has been widely used for device planarization. In order to meet the stringent gap filling requirements as the device evolves toward smaller feature sizes, the current BPSG deposition process using ozone/tetraethoxysilane chemistry was fully characterized to explore its extendibility for achieving high aspect ratio gap filling. Based on the characterization results, a two-layer film deposition process was developed to accommodate the gap filling capability as well as the system throughput. Without stretching the thermal budget, the current process is able to achieve void-free gap filling at a >6:1 aspect ratio, 0.06 μm width, even with reentrant profile. Other film properties, including film stress, moisture absorption, dopant profile and flow, were also studied extensively. Postdeposition film reflow can be performed using either conventional furnace or rapid thermal annealing, the reflowed profile depends on annealing temperature as well as ambient gases. A low thermal budget can be maintained using a steam anneal.

High Temperature Subatmospheric Chemical Vapor Deposited Undoped Silicate Glass: A Solution for Next Generation Shallow Trench Isolation

Undoped silicate glass deposited using the tetraethylorthosilicate (TEOS) and ozone thermal reaction has been selected as one of the candidates for shallow trench isolation applications. As a replacement for existing low pressure or atmospheric pressure chemical vapor deposition processes for device dimensions below 0.25 μm, TEOS/ozone films deposited at high temperature (>550°C) exhibit the superior qualities in terms of void-free trench fill. In this paper, we present some characterization of the silicon oxide film deposited in the subatmospheric pressure regime using TEOS/ozone chemistry, aimed at developing a high-quality dielectric film to meet shallow trench isolation gap-fill requirements. It is also identified that low ozone/TEOS ratio reduces surface and pattern sensitivity. Therefore, no additional treatment or predeposition is necessary. Moreover, to enhance the etch resistance of the silicon oxide, the as-deposited film is annealed at high temperature for densification and bond reconstruction.

Moisture Resistance of Plasma Enhanced Chemical Vapor Deposited Oxides Used for Ultralarge Scale Integrated Device Applications

The moisture resistance of plasma enhanced chemical vapor deposited (PECVD) oxide films used in ultralarge scale integrated (ULSI) device applications has been characterized using infrared (IR) spectroscopy. The differences in the moisture absorption characteristics between tetraethylorthosilicate (TEOS) and silane-based PECVD oxides are presented. Our results indicate that the film thickness and the as-deposited film stress are important factors in controlling the moisture resistance of these PECVD oxides; the deposition of these PECVD oxides using higher O 2 :TEOS ratios enhances moisture resistance; the use of N 2 O instead of O 2 as the oxidizing agent incorporates nitrogen as well as Si-H bonds in the film which enhance moisture resistance, and that an in situ N 2 plasma post-treatment of PECVD TEOS-O 2 films improves the moisture barrier characteristics of the these oxide films

Process Characteristics for Subatmospheric Chemical Vapor Deposited Borophosphosilicate Glass and Effect of Carrier Gas

Borophosphosilicate glass (BPSG) has been widely used as a premetal dielectric to achieve excellent gap fill and planarization due to its reflow capability. In this paper, we present some characterizations of subatmospheric chemically vapor deposited BPSG, aiming at developing a mechanistic understanding of this process. By comparing the effect of controlling variables on the film properties of BPSG and undoped silicon oxide, we conclude that this deposition process is controlled by the gas-phase diffusion of the reaction intermediates on the Si substrate. Therefore, chamber pressure and susceptor spacing are the two major process variables other than the reactant flows. The helium carrier gas process shows better film properties in terms of high deposition rate, smooth film, and good reflow capability.

Integration and Characterization of Low Carbon Content SiO x C y H z Low κ Materials for < 0.18μm[ Dual Damascene Application

A CVD-based low κ film was evaluated for inter-metal dielectric in x C y H z , where the carbon content was less than 5 atomic %. Blanket film integration study was conducted to find out the manufacturing compatibility. The largest increase in κ value occurred during etching and ashing steps. However, SIMS compositional analysis revealed that the damage from these steps were limited to within top 300 A, and the initial low κ value was recovered after the top damaged layer was removed by CMP. The final integrated dielectric constant was less than 3.0. The film density was measured as 1.4, compared to 2.3 g/cm 3 of conventional SiO 2 . The low density of the film resulted from the termination of SiO 2 network structures by Si-CH 3 and Si-H.

Multi-generation CVD low /spl kappa/ films for 0.13 /spl mu/m and beyond

After several delays in the implementation of /spl kappa/<3.0 inter metal dielectric, the semiconductor industry has finally begun to use these low /spl kappa/ materials in manufacturing in 2001. After several years of intense industry wide evaluation and assessment, the most critical requirements for these materials were identified to be high mechanical strength, low cost, high productivity and extendibility to at least another generation. CVD low /spl kappa/ films, IMD film black diamond (BD) and barrier/etch stop film BLO/spl kappa/, have become the materials of choice for 0.13 /spl mu/m an below generation IMD because of their silicon oxide like materials properties, proven manufacturability using time-tested familiar PECVD tool sets, and the recently proven extendibility to /spl kappa/<2.5. This paper focuses on the characteristics and performance of these materials both in Cu damascene integration and in production environment.

Stress-Temperature Behavior of O 3 -TEOS Sub-Atmospheric CVD (SACVD) Oxide Films Deposited on Various Oxide Underlayers

A systematic evaluation of the stress-temperature behavior of O 3 -TEOS Sub-Atmospheric CVD (SACVD) oxide films used in IMD applications was performed in order to elucidate the surface dependence and mechanical stability of these films when deposited on different oxide underlayers such as PECVD TEOS-based, Silane-based, and thermally grown oxides. SACVD films were deposited at 360°C using different O 3 :TEOS molar flow ratios. The results obtained in this study indicate that the stress-temperature behavior of SACVD films deposited on PECVD Silane-based and TEOS-based oxides using N 2 O as the oxidizing agent is similar to that of the SACVD films deposited on silicon. However, a large stress hysteresis is obtained when SACVD films are deposited on PECVD TEOS-O 2 and thermally grown oxide underlayers. This large stress hysteresis results from the surface dependence effects of the SACVD oxides on thermally grown and PECVD TEOS-O 2 oxide underlayers. Also, this stress hysteresis can be reduced or eliminated by treating the oxide underlayer surface with an in-situ Ar, He, or N 2 plasma. Furthermore, it was also found that the SACVD oxides deposited using higher O 3 :TEOS molar flow ratios are chemically and mechanically more stable.