CN111584359A - A kind of ultrasonic wet etching method based on ALD deposition Al2O3 as mask - Google Patents

Abstract

The invention discloses an ultrasonic wet etching method based on ALD deposition of Al ₂ O ₃ as a mask. The steps of the method are as follows: the first step, using atomic deposition technology (ALD) to deposit an Al ₂ O ₃ film on the surface of the III-V alloy semiconductor device sample; the second step, using photolithography and etching technology to selectively etch Al ₂ O ₃ to form an Al ₂ O ₃ mesa pattern mask; the third step is to perform wet etching while ultrasonically in an ultrasonic cleaner to etch the desired mesa; the fourth step, use BOE etching solution to remove Al ₂ O ₃ masks. The advantages of the present invention are: on the one hand, using ALD to deposit Al ₂ O ₃ instead of photoresist as a mask to prevent the phenomenon of degumming due to excessive wet etching time or ultrasonic vibration; Wet etching can prevent conductive residues from accumulating on the side of the step and form a conductive channel, effectively reducing the dark current density of the device and improving the performance of the device.

Description

A kind of ultrasonic wet etching method based on ALD deposition Al2O3 as mask

technical field

The invention relates to a process manufacturing technology for semiconductor devices, in particular to an ultrasonic wet etching method based on ALD deposition of Al ₂ O ₃ as a mask. , The side of the step is easily enriched with conductive substances, which leads to the problem of surface leakage, thereby reducing the dark current density of the device and improving the performance of the device.

Background technique

III-V alloy semiconductors (especially InAs, InSb, InAsSb, etc.) have excellent characteristics such as fast response speed, high carrier mobility and low room temperature Auger recombination coefficient, and the forbidden band width can cover There are two atmospheric windows of mid-wave infrared and long-wave infrared, so it has great advantages in the preparation of room temperature infrared detectors [1-2]. At present, in the preparation of III-V alloy semiconductor mesa devices, wet etching method is often used because of its advantages of simple operation, good selectivity and little damage to the device. However, the common photoresist mask is easily degummed when etched in the corrosive solution for a long time or under ultrasonic vibration, and the III-V alloys will also appear conductive substances enriched on the side of the step during the etching process. phenomenon, resulting in leakage on the surface of the device and performance degradation.

Atomic deposition (ALD) is a method of forming thin films by alternately pulsing gas-phase precursors into the reaction chamber and generating gas-solid phase chemical adsorption reactions on the surface of the deposition substrate [3]. ALD method is used to deposit Al ₂ O ₃ film on the surface which has stronger bonding force and is not easily corroded by the etching solution of wet etching III-V alloys as a mask, and wet etching is carried out in an ultrasonic environment, which can reduce the amount of etching. The conductive material on the side after etching is left, which reduces the dark current density of the device and improves the performance of the device. The cited literature is as follows:

[1] A. Venter, P. Shamba, L. Botha, et al. Growth and electrical characterization of Zn-doped InAs and InAs _1-x Sb _x [J]. Thin Solid Films, 2009, 517:4468-4473.

[2]R.Lal,P.Chakrabarti.A comparison of dominant recombinationmechanisms in n-type InAsSb meterials[J].2006,52:33-39.

M.Ritala,et al,Crystallinity ofinorganicfilms grown by atomic layer deposition:Overview and general trends,Journal ofApplied Physics,113(2013)021301.[3] V. Miikkulainen, M.

M. Ritala, et al, Crystallinity of inorganicfilms grown by atomic layer deposition: Overview and general trends, Journal of Applied Physics, 113(2013) 021301.

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose an ultrasonic wet etching method based on ALD deposition of Al ₂ O ₃ as a mask to improve the problem that conductive substances are easily enriched on the side of III-V alloy semiconductor mesa devices after wet etching steps , thereby reducing the dark current density of the device and improving the device performance.

The specific steps of using the method of the present invention are:

The first step is to deposit an Al ₂ O ₃ film on the surface of the III-V alloy semiconductor device sample using the atomic deposition technique ALD, and the thickness of the film is 100-200 nm;

In the second step, photolithography and etching processes are used to selectively etch Al ₂ O ₃ to form an Al ₂ O ₃ mesa pattern mask;

In the third step, wet etching is performed while ultrasonically in an ultrasonic cleaner to etch out the required mesa. The ultrasonic frequency is 40KHz, and the ultrasonic power is 25-35W;

The fourth step is to remove the Al ₂ O ₃ mask using BOE etching solution.

The advantages of the present invention are: on the one hand, using ALD to deposit Al ₂ O ₃ instead of photoresist as a mask to prevent the phenomenon of degumming due to excessive wet etching time or ultrasonic vibration; Wet etching can prevent conductive residues from accumulating on the side of the step to form a conductive channel, effectively reducing the dark current density of the device and improving the performance of the device.

Description of drawings

FIG. 1 is a flow chart of ultrasonic wet etching of the mesa with Al ₂ O ₃ as a mask.

Figure 2 shows the I-V curves of III-V alloy semiconductor devices prepared by different mesa etching methods.

Detailed ways

The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings, but are not intended to limit the present invention.

Firstly, the pn junction of group III-V alloy semiconductor is selected as the device sample, and the Al ₂ O ₃ film is deposited on the surface of the sample by ALD technology, with a thickness of 100-200 nm. The Al source is trimethylaluminum (TMA), and the O source is Water (H ₂ O), according to the temperature tolerance of the device sample, the growth temperature can be 150°C or 300°C: 150°C can be selected for those sensitive to high temperature to reduce damage to the device sample, while the device sample that is not sensitive to high temperature can be selected at 150°C , you can choose 300 ℃, the grown film is more dense; secondly, using photolithography and etching process, use BOE etching solution to selectively etch away the Al ₂ O ₃ film outside the mesa pattern to form an Al ₂ O ₃ mesa pattern mask, And remove the residual photoresist; then, the device sample using the Al ₂ O ₃ film as a mask is subjected to wet etching of III-V alloy semiconductors in an ultrasonic environment to carve out a mesa with a desired height. The ultrasonic etching time depends on the height of the steps to be etched. The ultrasonic frequency is 40KHz, and the power can be 25W, 30W or 35W. The higher the power, the faster the etching rate and the shorter the time required. Finally, the Al ₂ O ₃ mask is removed using a BOE etchant.

Claims (1)

1. a kind of ultrasonic wet etching method based on ALD deposition Al ₂ O ₃ makes mask, it is characterized in that method steps are as follows: The first step is to deposit an Al ₂ O ₃ film on the surface of the III-V alloy semiconductor device sample using the atomic deposition technique ALD, and the thickness of the film is 100-200 nm; In the second step, photolithography and etching processes are used to selectively etch Al ₂ O ₃ to form an Al ₂ O ₃ mesa pattern mask; The third step is to perform wet etching while ultrasonically in the ultrasonic cleaning machine to etch the required mesa, the ultrasonic frequency is 40KHz, and the ultrasonic power is 25-35W; The fourth step is to remove the Al ₂ O ₃ mask using BOE etching solution.

Images