摘要:
A method of manufacturing a HEMT IC using a citric acid etchant. In order that gates of different sizes may be formed with a single etching step, a citric acid etchant is used which includes potassium citrate, citric acid and hydrogen peroxide. The wafer is first spin coated with a photoresist which is then patterned by optical lithography. The wafer is dipped in the etchant to etch the exposed semiconductor material. Metal electrodes are evaporated onto the wafer and the remaining photoresist is removed with solvent.
摘要:
A single-layer, metal-insulator-metal capacitor, a monolithic microwave integrated circuit including such capacitors, and a process of fabricating such capacitors. The capacitor has a single layer of insulating material between two metallic layers. At least one of the metallic layers has rounded corners, reducing the electric field at the corners, and so lessening the likelihood of breakdown. In one preferred embodiment, each metal layer has rounded corners. The capacitors can be fabricated by an optical lithographic process.
摘要:
Antimony-based semiconductor devices are formed over a substrate structure (10) that includes an antimony-based buffer layer (24) and an antimony-based buffer cap (26). Multiple epitaxial layers (30–42) formed over the substrate structure (10) are dry etched to form device mesas (12) and the buffer cap (26) provides a desirably smooth mesa floor and electrical isolation around the mesas.
摘要:
A method of using bias-dependent S-parameter measurements as a form of microscopy. The microscopy can be used to resolve the details of the internal charge and electric field structure of a semiconductor device. Like other forms of microscopy, the S-parameter microscopy focuses on pseudo “images” and provides a contrast in the “images”. Essentially, the images are gathered in raw form as S-parameter measurements and extracted as small signal models. The models are used to form charge control maps, through a selective method analogous to focusing. Focusing is provided by an algorithm for the unique determination of small signal parameters with contrasts provided by utilizing measured bias dependent activity to discriminate boundaries between the electrical charge and fields. As such, the system is able to accurately forecast semiconductor performance.
摘要:
A semi-physical device model for HEMTs that can represent known physical device characteristics and measured high frequency small signal characteristics relatively accurately. The semi-physical device model in accordance with the present invention uses analytical expressions to model the fundamental electric charge and field structure of a HEMT internal structure. These expressions are based on the device physics but are in empirical form. In this way, the model is able to maintain physical dependency with good fidelity while retaining accurate measured-to-modeled DC and small signal characteristics. The model in accordance with the present invention provides model elements for a standard small signal equivalent circuit model of FET. The model elements are derived from small signal excitation analysis of intrinsic charge and electric field as modeled within the device by the semi-physical HEMT model. As such, the RF performance can be predicted at arbitrary bias points.
摘要:
A hybrid model formed from a semi-physical device model along with an accurate data-fitting model in order to implement a relatively accurate physical device model as a large signal microwave circuit computer-aided design (CAD) tool. The semi-physical device model enables accurate representation of known physical device characteristics and measured bias-dependent characteristics. This model is used to accurately simulate the effect of process variation and environmental changes on bias-dependent characteristics. The data-fitting model is used to model these characteristics with relatively good fidelity. The expressions of the model are constructed to be charge conservative. As such, the model is computationally robust within the harmonic balance algorithms employed by known large signal microwave circuit CAD tools.
摘要:
A semiconductor device is provided that comprises a base structure, a first channel layer overlying the base structure, a second channel layer overlying the first channel layer, and first, second, and third ohmic contacts overlying the second channel layer. The semiconductor device further comprises a metal-semiconductor heterodimension field effect transistor that is formed between the first and second ohmic contacts, the metal-semiconductor heterodimension field effect transistor including a first gate formed through the first and second channel layers. The semiconductor device yet further comprises a high electron mobility transistor formed between the second and third ohmic contacts, the high electron mobility transistor including a second gate formed through the second channel layer without extending through the first channel layer.
摘要:
A model for a semiconductor device and more particularly to a Pi-FET with multiple gate fingers. The model takes into account various parasitics and the inter-relationship therebetween. In particular, multi-finger Pi-FETs are modeled as multiple single finger unit cells. Each single unit cell takes into account off-mesa parasitics, inter-electrode parasitics, on-mesa parasitics and includes an intrinsic model which represents the physics that predominantly determine FET performance. As such, the model can be used for relativity accurate device technology modeling, optimization of device performance and device design.