Abstract:
A method for selectively oxidizing the surface of a III-V compound semiconductor wafer. A photoresist mask is first formed on the surface of the semiconductor leaving exposed the areas to be oxidized. The semiconductor is then made the anode in an electrolytic cell wherein the electrolyte comprises water and a source of ions for adjusting the pH or providing conductivity to the solution. In a preferred embodiment, the wafer is a gallium containing compound semiconductor and in particular GaAs, and the electrolyte is water and an ammonium acid phosphate. The oxide is grown electrolytically only into the exposed areas of the wafer, and the photoresist may then be stripped off leaving the desired oxide pattern.
Abstract:
A method of forming a composite oxide on III-V compound semiconductors is disclosed. An oxidizable metal such as Al, Ni, Ta, Ti, Zn or alloys including said metals is deposited on the surface of the semiconductor or on a native oxide grown on the semiconductor. The structure is subjected to an electrolytic oxidation so that all the metal is oxidized and a native oxide is grown into the surface resulting in a composite oxide comprising the native oxide and the metal oxide. This composite oxide can serve to passivate the semiconductor as well as provide a stable mask for etching and diffusion processes. In addition, the composite oxide appears to have a high dielectric strength for use in MOS devices.
Abstract:
A LOW WORK FUNCTION SCHOTTKY BARRIER DIODE IS OBTAINED BY COATING A CONTACT REGION UPON A GALLIUM ARSENIDE SUBSTRATE WITH A TIN HALIDE FLUX AND SUBSEQUENTLY DEPOSITING TIN THEREON.
Abstract:
A method for oxidation and etching of a III-V compound semiconductor in a single solution. The semiconductor is made the anode in an electrolytic cell wherein the electrolyte is water raised to a pH of 8 or above by a source of hydroxyl ions such as NH4OH. When an appropriate electric field is established in the cell, an oxide is grown into the surface of the semiconductor. Then the field is lowered or turned off and the oxide dissolves faster than it is grown resulting in an etching of the semiconductor material previously consumed in forming the oxide. The method permits electrochemical thinning of a semiconductor layer for such uses as FETS and IMPATTS and further allows formation of passivating layers on etched surfaces in situ.
Abstract:
A method of forming a highly stable oxide on gallium arsenide containing compound semiconductors. A native oxide is grown on the surface of the semiconductor and dried during a suitable baking cycle. The oxide is then annealed at a temperature which is significantly higher than that of the baking cycle. This annealing step densifies the oxide and renders it particularly stable and impervious to impurities. In a particular embodiment, a diffusion mask is formed in accordance with the invention to permit selective area diffusion of impurities into a gallium arsenide containing compound semiconductor.
Abstract:
A method for protecting the surface of GaAs junction lasers, in particular the cleaved mirror surfaces of such devices. A native oxide is first grown on the surface of the device by immersing the device in an aqueous H2O2 solution wherein the pH is 1.5-3.5. The device is then immersed in an aqueous H2O2 solution which has been adjusted to a pH of 6-8 by a suitable hydroxide. This double oxidation technique provides substantial protection against the deleterious effects of water on the mirror surfaces.
Abstract translation:一种用于保护GaAs结激光器表面的方法,特别是这种器件的切割镜面。 首先通过将该装置浸入pH为1.5-3.5的H 2 O 2水溶液中,在该装置的表面上生长天然氧化物。 然后将该装置浸入H 2 O 2水溶液中,该水溶液通过合适的氢氧化物调节至pH为6-8。 这种双重氧化技术提供了大量的保护,防止水对镜面的有害影响。
Abstract:
A method of fabricating dielectric optical waveguides comprises the steps of: (1) fabricating a single or double heterostructure from the GaAs-AlGaAs system preferably by liquid phase epitaxy or molecular beam epitaxy; (2) forming a native oxide layer on the top surface of the heterostructure by anodization in H2O2; (3) removing a portion of the oxide layer to form a mask and hence to define the waveguide shape in the direction of light propagation; and (4) forming a mesa-like structure with optically flat side walls by etching at a slow rate in Br2-CH3OH. After step (4) two alternative techniques leading to structurally different waveguides may be followed. In one technique, an AlGaAs layer is epitaxially grown over the mesa to form a two dimensional waveguide. In the other technique, the edges of the active region of an AlGaAs double heterostructure are differentially etched in a neutral solution of H2O2. The latter step is particularly useful in the fabrication of active devices because the resulting structure is self-masking, thereby facilitating the formation of electrical contacts.
Abstract translation:制造介质光波导的方法包括以下步骤:(1)优选地通过液相外延或分子束外延从GaAs-AlGaAs系统制造单或双异质结构; (2)通过阳极氧化在H 2 O 2中在异质结构的顶表面上形成天然氧化物层; (3)除去氧化物层的一部分以形成掩模,从而在光传播的方向上限定波导形状; 和(4)通过在Br 2 -CH 3 OH中以缓慢的速率蚀刻形成具有光学平坦侧壁的台面状结构。 在步骤(4)之后,可以遵循导致结构不同的波导的两种替代技术。 在一种技术中,在台面上外延生长AlGaAs层以形成二维波导。 在另一种技术中,AlHAs双异质结构的有源区的边缘在H 2 O 2的中性溶液中进行差分蚀刻。 后一步骤在制造有源器件中特别有用,因为所得到的结构是自掩蔽的,从而有助于电接触的形成。
Abstract:
A method is described which permits electrolytic oxidation of semiconductor samples with contact metallization in place. An anodizable metal such as Al, Ni, Ta, Ti, Zn or alloys including such metal is deposited over the contacts. During electrolytic oxidation, the oxide formed over the metal closes off shunting paths which would normally exist through the contacts and thereby permits a native oxide to grow into the exposed surface of the semiconductor. The oxide formed over the metal can be easily cracked under mechanical pressure to permit electrical connection to the contacts in the final device.
Abstract:
A method for precisely tailoring the thickness of a layer of semiconductor material in a structure comprising regions of varying doping concentrations in order to achieve desired uniform electrical properties. The method involves, generally, electrolytically thinning the layer to remove the semiconductor material until a desired field distribution in the structure is reached. In one embodiment, an FET with an epitaxial layer on a semi-insulating substrate is manufactured by successively oxidizing the epitaxial layer and dissolving the oxide until the depletion region resulting from the applied potential extends into the semi-insulating substrate and oxide growth stops. This results in a uniform pinch-off condition along the layer regardless of the original non-uniformity in the epitaxial layer. In a further embodiment, the epitaxial layer in an IMPATT structure is thinned by successive oxidation and dissolution until the voltage dropped across the semiconductor is equal to the applied potential and again oxide growth stops. This procedure results in a desired uniform breakdown voltage for the wafer.