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Epoxy resin is usually used as an encapsulation of electronic parts. Epoxy resin is transformed from liquid to solid by the chemical curing reaction, and then residual stress and warpage are generated in the electronic parts. Therefore, the generation mechanism is clarified and it is necessary to establish the evaluation method. In this report, the chemical reaction of epoxy resin was generated and the amount of the warpage caused by the curing process was verified by the experiment. As a result, the simplified evaluation method of the amount of the warpage caused by the chemical reaction was established, and it was clarified that the experimental value of residual warpage could be explained by adding the value of curing warpage by the evaluation method and thermal warpage by the thermal viscoelastic analysis.

Epoxy resin is usually used as an encapsulation of electronic parts. Epoxy resin is transformed from liquid to solid by the chemical curing reaction, and then residual stress and warpage are generated in the electronic parts. Therefore, the generation mechanism is clarified and it is necessary to establish the evaluation method. In this report, the chemical reaction of epoxy resin was generated and the amount of the warpage caused by the curing process was verified by the experiment. As a result, the simplified evaluation method of the amount of the warpage caused by the chemical reaction was established, and it was clarified that the experimental value of residual warpage could be explained by adding the value of curing warpage by the evaluation method and thermal warpage by the thermal viscoelastic analysis.

A new measurement method for curvature distribution of warped SiO_2-GaAs substrate using differential diffraction angles with respect to a standard rocking curve for flat substrate is presented. These rocking curves are measured by x-ray double crystal method for each reflection from the points which are selected at regular intervals on the specimen by moving the slit placed in front of the specimen. The measurement method is applied at room temperature to three cases of SiO_2-GaAs substrate whose SiO_2 film has been deposited uniformly by CVD at 350℃. These three cases are: i) SiO_2 film deposited on the whole substrate, ii) SiO_2 film partially removed, iii) SiO_2 film completely removed. The results of measurements reveal the following facts. SiO_2-GaAs substrate is warped uniformly independent of the distribution of the lattice defects in the substrate due to the difference of thermal expansion coefficient between SiO_2 film and GaAs crystal. Namely the SiO_2 film on the GaAs crystal is in a state of compression. There is an appreciable difference of the curvature between those for SiO_2 film deposited area and SiO_2 film removed area.

A new measurement method for curvature distribution of warped SiO_2-GaAs substrate using differential diffraction angles with respect to a standard rocking curve for flat substrate is presented. These rocking curves are measured by x-ray double crystal method for each reflection from the points which are selected at regular intervals on the specimen by moving the slit placed in front of the specimen. The measurement method is applied at room temperature to three cases of SiO_2-GaAs substrate whose SiO_2 film has been deposited uniformly by CVD at 350℃. These three cases are: i) SiO_2 film deposited on the whole substrate, ii) SiO_2 film partially removed, iii) SiO_2 film completely removed. The results of measurements reveal the following facts. SiO_2-GaAs substrate is warped uniformly independent of the distribution of the lattice defects in the substrate due to the difference of thermal expansion coefficient between SiO_2 film and GaAs crystal. Namely the SiO_2 film on the GaAs crystal is in a state of compression. There is an appreciable difference of the curvature between those for SiO_2 film deposited area and SiO_2 film removed area., 紀要論文

A new method for measuring the surface concentration of the diffused impurity atoms is proposed. Because of the lattice distortion due to the distribution of the diffused impurity atoms, the substrate crystal is warped like bimetals. The equations to calculate the warpage angle of the substrate crystal are derived. The surface concentration of the diffused impurity of the substrate is decided so that the value calculated by the equations fits in the measured value of the warpage angle. The method was actually applied to {l00} GaAs substrates in which Cd atoms had been diffused at 1000℃ and 900℃ respectively. The calculated values of the warpage angle of the substrate assuming the complementary error function for the Cd distribution are in good agreement with the experimental values. The Cd-surface concentrations diffused at 1000℃ and 900℃ were decided as 1.3×10^ and 2×10^cm^, respectively. For the reduction of the warpage angle when the diffused layer was removed, the theoretical values were also in good agreement with the experimental values. From these facts, therefore, the validity of the assumption of the complementary error function for the Cd-distribution were confirmed., 紀要論文

A bimetallic model is proposed in measurement of very small difference rate of lattice constant Δa/a between epitaxial layer and the substrate of the epitaxial layer/substrate structure. It is predicted theoretically that Δa/a of the specimen can be measured up to the order of 10^ by this method, if the epitaxial layer is thicker than 3μm. The method is applied to non-doped GaAs epitaxial layer / Cr-doped GaAs substrate structure. Δa/a of the specimen is 1.7×10^ and the lattice constant of the non-doped GaAs is slightly larger than that of Cr-doped GaAs. The concentration of Cr (9.4ppm) obtained from this lattice constant difference does not agree with the doping concentration of Cr(0.1-0.5ppm) in the substrate. This suggests that some other lattice defects are contained in the specimen. The method can not be appled to the specimen with the scratched surface, because such specimen warps abnormally with reducing the thickness., 紀要論文